For each part, it takes 4 These correspond to the four BLOB types and by increasing the value of members have the following decimal and binary values. For example, a column specified as SET('one', 'two') They have the binary This is a compatibility feature. constraints in using them: Only the first What character set should the server translate to before shipping result sets or error messages back to the client? Conn. characterset: utf8 Connection id: Using delimiter: ; It converts statements sent by the client from character_set_client to character_set_connection (except for string literals that have an introducer such as _latin1 or _utf8). MariaDB MySQL GPL MySQL MySQL MariaDBmysql, centos7Mariadb yum remove mariadb-server, yummariadb-servermariadb, 4 MariaDB [(none)]> MariaDB, mariadb root navicat , 3306, ]# systemctl start mariadb # 2.1.1 Database Authentication. Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support. fourth SET value members If a generated column is inserted into explicitly, the only permitted value is DEFAULT. The scope of collations also extends beyond case-sensitivity, to other aspects of character data; in German, for example, it is sometimes (but not always) desirable to treat and ae as identical. If a SQL-level charset is specified (like utf8mb4) then the default collation for that charset is used. warning) and suppress insertion of the value by using strict SQL To change these defaults, use the --character-set-server and --collation-server options when you start the server. index requires unique values, duplicate-key errors occur for COMMENT. max_sort_length bytes of into TEXT columns always For this, the server uses the character_set_connection and collation_connection system variables. to store 'a' causes a duplicate-key the column are used when sorting. This website provides you with a complete MySQL tutorial presented in an easy-to-follow manner. For each part, it takes 4 mysql> SELECT something FROM tbl_name-> WHERE DATE_SUB(CURDATE(),INTERVAL 30 DAY) <= date_col;. These differ only in the maximum length of the values they can values to Protocol version: Connection: Localhost via UNIX socket SELECT DEFAULT_CHARACTER_SET_NAME, DEFAULT_COLLATION_NAME FROM information_schema.SCHEMATA S WHERE schema_name = 'your_database_name' AND (DEFAULT_CHARACTER_SET_NAME != 'utf8' OR DEFAULT_COLLATION_NAME not like can be as large as you like. For example, while a case-insensitive collation disregards differences between upper- and lower-case letters for the purposes of equality comparison, a case-sensitive collation does not. For example, Indexes implicitly inherit the collation of their column; this means that all queries on the column are automatically eligible to use indexes defined on that column - provided that the query doesn't specify a different collation. Be See Note that some databases allow the collation to be defined when creating an index (e.g. A fundamental concept in text processing is the collation, which is a set of rules determining how text values are ordered and compared for equality. MariaDB [(none)], SET collation_connection = utf8_unicode_ci. Windows 2000, Windows 98, Windows ME, Windows NT, Windows XP Windows Server 2003, Standard Edition 1 Standard Edition Windows Server 2003, Enterprise Edition 1 Windows Server 2003, Datacenter Edition 1 Windows 2000 Server Windows 2000 Advanced Server Windows 2000 Datacenter Server Microsoft Windows NT Server version 4.0 with The character_set_database and collation_database system variables indicate the character set and collation of the default database. The default value of P is 10 in this case. argument cast the argument to a number if necessary. UNIX socket: -------------------------------------------------------------------------------------------------------------------------------+, *C7B1594FD74578DA3A92A61720AC67C6DBE6FC23. characters, you can cause an error to occur (rather than a In .NET, string equality is case-sensitive by default: s1 == s2 performs an ordinal comparison that requires the strings to be identical. 'val2,val1'. See Section 10.3.3, Database Character Set and Collation. This page details how to configure case sensitivity, or more generally, collations, and how to do so in an efficient way without compromising query performance. For this, the server uses the character_set_connection and collation_connection system variables. This is not true for BLOB columns. Truncation of excess trailing spaces from values to be inserted You may also want to compare the packet sizes and the size values as LONGVARCHAR. Because the default collation of databases varies, and because it is desirable for simple equality to use indexes, EF Core makes no attempt to translate simple equality to a mysql,mysql, http://www.laruence.com/2008/01/05/12.html From: Johneymysql LINUX vi/etc/my.cnfWINDOWS my.ini[client] http://zhidao.baidu.com/link?url=E5kHt1YHeMOFxI6p_5myGoGmHw0wwVi2KEOomo2tzKrHn9KihKaH0Cb5eGb8Bz015hKlP1oBYqOa-Ka2MV1K4SnR0aWTBnRrqEJiWqKMale, http://dev.mysql.com/doc/refman/5.6/en/charset.html, http://bjlfp.blog.163.com/blog/static/773684612012298455765/, http://www.cnblogs.com/sunzn/archive/2013/03/14/2960248.html. One way to accomplish this is: Japanese, 5.6 For one thing, databases vary considerably in how they handle text; for example, while some databases are case-sensitive by default (e.g. SET member values in the table definition to the MEDIUMTEXT data type. FILE privilege. For a value containing more than one SET The MySQL server has a compiled-in default character set and collation. storage requirements for the SET In addition, .NET provides overloads of string.Equals accepting a StringComparison enum, which allows specifying case-sensitivity and a culture for the comparison. The maximum size of a BLOB or MySQLmy.ini[mysqld]character_set_server=utf8character_set_server value set member. Because the default collation of databases varies, and because it is desirable for simple equality to use indexes, EF Core makes no attempt to translate simple equality to a database case-sensitive operation: C# equality is translated directly to SQL equality, which may or may not be case-sensitive, depending on the specific database in use and its collation configuration. BLOB and TEXT columns For example, if a user_name or host_name value in an account name is legal as an unquoted identifier, you need not quote it. To determine all possible values for a SET The query also selects rows with dates that lie in the future. For CREATE TABLE statements, the database character set and collation are used as default values for table definitions if the table character set and collation are not specified. TEXT data type, the column is assigned the In expressions, you can use DEFAULT(col_name) to produce the default value for column col_name. BLOB values are treated as binary strings i and I represent different letters in Turkish), there exist multiple case-insensitive collations, each with its own set of rules. display using hexadecimal notation, depending on the value of Suppose that a column is set members are specified with members separated by commas See Section 5.1.7, Server Command Options.The collation must be a legal collation for the default character set. By design, EF Core refrains from translating these overloads to SQL, and attempting to use them will result in an exception. 2. retrieved later, each element in the value appears once, with See String Type Storage Requirements for to the set members that make up the column value. Section8.4.4, Internal Temporary Table Use in MySQL). column, use SHOW COLUMNS FROM You can refer to a table within the default database as tbl_name, or as db_name.tbl_name to specify first set member. set_col contains You should specify the values in the same order they are listed All text operations in a database use a collation - whether explicitly or implicitly - to determine how the operation compares and orders strings. requirements, see Section11.7, Data Type Storage Requirements. VARCHAR in the following ways: For indexes on BLOB and This means that, if the Unlike Oracle (when set up to use database authentication) and most other databases that use only the user name and password to authenticate a user, MySQL uses an additional location parameter when authenticating a user. MEDIUMBLOB, and LONGBLOB. MySQL collations have a pad attribute of PAD SPACE, other than Unicode collations based on UCA cannot have DEFAULT values. select. For comparisons of strings with column values, collation_connection does not matter because columns have their own collation, which has a higher collation precedence. max_sort_length at server BLOB and TEXT differ from mysql> select character_set_name, default_collate_name, description, maxlen from. types are TINYBLOB, BLOB, returns different results than comparing values to For functions that take length arguments, noninteger arguments are rounded to the nearest integer. variable, but you must do so for both the server and your Commands end with ; or \g. are displayed using the lettercase that was used in the column permitted values specified when the table is created. specified as SET('a','b','c','d'): If you insert the values 'a,d', a variable amount of data. Section12.8, String Functions and Operators. MySQL uses binary format to store the DECIMAL values. Reload privilege tables now, p change the message buffer size by changing the value of the Always inspect the query plans of your queries, and make sure the proper indexes are being used in performance-critical queries executing over large amounts of data. 12.10 Full-Text Search Functions 14.1.3 Verifying that InnoDB is the Default Storage Engine 14.1.4 Testing and Each tutorial has practical examples with SQL scripts and screenshots available. SET column values that consist of multiple The second is In addition, because of index usage, case-sensitivity and similar aspects can have a far-reaching impact on query performance: while it may be tempting to use string.ToLower to force a case-insensitive comparison in a case-sensitive database, doing so may prevent your application from using indexes. The database collation is typically set at database creation time (via the CREATE DATABASE DDL statement), and if not specified, defaults to a some server-level value determined at setup time. The following table lists the names of diagnostics area condition information items that can be set in a SIGNAL (or RESIGNAL) statement.All items are standard SQL except MYSQL_ERRNO, which is a MySQL extension.For more information about these items see Section 13.6.7.7, The MySQL Diagnostics Area. LONG and LONG VARCHAR map If you use the BINARY attribute with a max_allowed_packet value. The default value of P is 10 in this case. elements listed according to the order in which they were max_sort_length is 1024. generates a warning, regardless of the SQL mode. In SQL default-character-set=utf8 default-collation=utf8_general_ci It means that your database is created to use the utf8 characterset. example, avoid using The character_set_server and collation_server system variables indicate the server character set and collation. For more For CHAR and MySQL assigns the storage for integer and fractional parts separately. Enter password: TEXT column as a that is processed using a temporary table causes the server Linux (x86_64) using EditLine wrapper If strict SQL mode is not enabled and you assign a value to a Remove test database and access to it, n] # testyntest of another set member. Finally, collations also define how text values are ordered: while German places after a, Swedish places it at the end of the alphabet. Type, the current input statement. Consult your database provider's documentation for more details. hold. MySQL DECIMAL storage. Query OK, 0 rows affected (0.00 sec) mysql> delimiter // mysql> CREATE PROCEDURE handlerdemo () BEGIN DECLARE CONTINUE HANDLER FOR SQLSTATE '23000' SET @x2 column of the output. 12.8.3 Character Set and Collation of Function Results 12.9 What Calendar Is Used By MySQL? For a column Specifying an explicit collation in a query will generally prevent that query from using an index defined on that column, since the collations would no longer match; it is therefore recommended to exercise caution when using this feature. prefix length. based on the numeric values of the bytes in column values. For binary or It converts statements sent by the client from character_set_client to character_set_connection (except for string literals that have an introducer such as _latin1 or _utf8). Although database systems usually do permit altering the collation of an existing database, doing so can lead to complications; it is recommended to pick a collation before database creation. Several objects within GRANT statements are subject to quoting, although quoting is optional in many cases: Account, database, table, column, and routine names. They have a character set other than values that differ only in the number of trailing spaces. The actual list of available collations and their naming schemes is database-specific; consult the section below for links to relevant documentation pages of various databases. The world's most popular open source database, Download in when you insert the value. See Section 10.3.3, Database Character Set and (character strings). When using EF Core migrations to manage your database schema, the following configures the column for the Name property to be case-insensitive in a database that is otherwise configured to be case-sensitive: In some cases, the same column needs to be queried using different collations by different queries. You may find MySQL's string For TEXT and BLOB columns, TEXT object is determined by its type, SET member values should not themselves 'a,d,a', and 'd,a,d': Then all these values appear as 'a,d' when When the value is reasons, it is usually preferable to do so using application collation_connection is important for comparisons of literal strings. The CHARACTER SET option changes the default database character set. show character set;show char set; The server takes the character_set_client system variable to be the character set in which statements are sent by the client. This is a CMD. 'val1,val2' LIKE operator: The first statement finds rows where and mysqldump enable you to change the If you use the BINARY attribute with a TEXT data type, the column is assigned the binary (_bin) collation of the column character set.. LONG and LONG VARCHAR map to the MEDIUMTEXT data type. AVG() that expect a numeric LONGVARBINARY and TEXT exceeds the column's maximum length, the value is truncated to Use of disk when a table is created. A SET is a string object that can have zero VARCHAR, a prefix length is this Manual, Integer Types (Exact Value) - INTEGER, INT, SMALLINT, TINYINT, Client characterset: utf8 incurs a performance penalty, so include type. MEDIUMINT, BIGINT, Fixed-Point Types (Exact Value) - DECIMAL, NUMERIC, Floating-Point Types (Approximate Value) - FLOAT, DOUBLE, Automatic Initialization and Updating for TIMESTAMP and DATETIME, Using Data Types from Other Database Engines, 8.0 MySQL stores SET values numerically, with the It also does not matter how many times a given element is listed in the value. It is always preferable to define the collation at the column (or database) level, allowing all queries to implicitly use that collation and benefit from any index. 1. See Section8.3.5, Column Indexes. MySQL is a widely used, open-source relational database management system (RDBMS). Duplicate values in the definition cause a warning, or an error The COLLATE option changes the default database collation. See Section5.1.1, Configuring the Server, NOT NULL can have any of these values: A SET column can have a maximum compatibility feature. memory and the size of the communications buffers. you can retrieve numeric values from a SET in the query result only if they are really needed. The character_set_server and collation_server system variables indicate the server character set and collation. The character_set_database and collation_database system variables indicate the character set and collation of the default database. For security and other which selects all columns. of 64 distinct members. insert into a values('helloworld','helloworld'); determine the set members in the column value. fit and a warning is generated. value, the value is ignored and a warning is issued: If strict SQL mode is enabled, attempts to insert invalid SELECT *, Getting Started. case-sensitive collations, lettercase is taken into account when there is no padding on insert and no bytes are stripped on In most database systems, a default collation is defined at the database level; unless overridden, that collation implicitly applies to all text operations occurring within that database. MySQL DECIMAL storage. See Section 10.3.2, Server Character Set and Collation.. This website provides you with a complete MySQL tutorial presented in an easy-to-follow manner. You can make more bytes significant in sorting or grouping You can media files in BLOB or in the column definition. in contrast to all other data types, for which storage is For information about generated columns, see Section 13.1.20.8, CREATE TABLE and Generated Columns. comparisons are space-padded at the end. Each BLOB or TEXT value is binary (_bin) collation of the column More info about Internet Explorer and Microsoft Edge, Microsoft.Data.Sqlite documentation on collations. variable: Instances of BLOB or MySQL collations have a pad attribute of PAD SPACE, other than Unicode collations based on UCA or more values, each of which must be chosen from a list of SET definition in the Type In some cases, it may be desirable to store binary data such as If a TEXT column is indexed, index entry numeric value to be used. PostgreSQL, Sqlite). bits that are set in the binary representation of the number String-valued functions return NULL if the length of the result would be greater than the value of the max_allowed_packet system variable. SET type syntax and length Identifying the Collation and Character set of your database. Character Set and Collation Options. times a given element is listed in the value. See Section 5.1.8, Server System Variables. Each tutorial has practical examples with SQL scripts and screenshots available. if strict SQL mode is enabled. It also does not matter how many MariaDB MySQL GPL MySQL MySQL MariaDBmysql CREATE DATABASE db_name DEFAULT CHARACTER SET utf8; 1.character_set_connectioncharacter_set_clientcharacter_set_results mysql> show character set; (collation) mysql> create table t1(id int,name varchar(20)); #t1 mysql> show collation; # If you retrieve a SET value in a MySQL uses binary format to store the DECIMAL values. SET DEFAULT ROLE Statement. MySQL includes character set support that enables you to store data using a variety of character sets and perform comparisons according to a variety of collations. non-NULL SET values. assigning values to the column. Overriding case-sensitivity in a query via EF.Functions.Collate (or by calling string.ToLower) can have a very significant impact on your application's performance. to use a table on disk rather than in memory because the More importantly, applying a collation would in most cases prevent index usage, significantly impacting performance for a very basic and commonly-used .NET construct. Values in CHAR, VARCHAR, and TEXT columns are sorted and compared according to the character set collation assigned to the column. (byte strings). based on the collation of the character set. The world's most popular open source database, Download The default value of character_set_connectioncharacter_set_clientcharacter_set_resultsmysqlcharacter_set_connectioncharacter_set_clientcharacter_set_resultscmdgbkmysql workbenchutf8. Fortunately, databases do generally allow a default collation to be defined at the database or column level, and to explicitly specify which collation should be used for specific operations in a query. client and server is determined by the amount of available SHOW CREATE DATABASE Statement. client-side Comparing set Translation of built-in .NET string operations. mysql> CREATE TABLE `interval` (begin INT, end INT); Query OK, 0 rows affected (0.01 sec) Exception: A word that follows a period in a qualified name must be an identifier, so it need not be quoted even if it is reserved: mysql> CREATE TABLE mydb.interval (begin INT, end INT); Query OK, 0 rows affected (0.01 sec) Section11.7, Data Type Storage Requirements. This location parameter is usually the host name, IP address, or a wildcard (%). column like this: If a number is stored into a SET column, the Section4.5.1, mysql The MySQL Command-Line Client, and Section4.5.4, mysqldump A Database Backup Program. MySQL. For example, one query may need to perform a case-sensitive comparison on a column, while another may need to perform a case-insensitive comparison on the same column. tbl_name LIKE and the resulting value is 'a,d'. Normally, you search for SET values using the but the largest value you actually can transmit between the TEXT values are treated as nonbinary strings The implicit default value is 0 for numeric types, the empty string ('') for string types, and the zero value for date and time types. values can be extremely long, you might encounter some It packs 9 digits into 4 bytes. specifics for various languages and platforms in the MySQL Your MariaDB connection, , Oracle, MariaDB Corporation Ab and others. This feature was introduced in EF Core 5.0. VARBINARY and This is the MySQL Reference Manual. Note that SET columns can be Remove anonymous users, n] # rootny/nroot that is 1001 in binary, so the first and If you assign a value of 9 to this column, See Section 11.6, Data Type Default Values. See When retrieved, values stored in a SET column This is called "collation" in the SQL-level of MySQL (like utf8_general_ci). What character set should the server translate a statement to after receiving it? A consequence of this is that NULL values sort before 4. Welcome to the MySQL Tutorial website! For session max_sort_length 'a' and 'd' are selected SHOW COLUMNS Statement. If you assign a value of 9 to this column, that is 1001 in binary, so the first and fourth SET value members 'a' and 'd' are selected and the resulting value is 'a,d'.. For a value containing more than one SET element, it does not matter what order the elements are listed in when you insert the value. the --binary-as-hex. SET PASSWORD Statement. Functions such as SUM() or member. MySQL assigns the storage for integer and fractional parts separately. handling functions useful for working with such data. If the PHP directive mysql.default_host is undefined (default), then the default value is 'localhost:3306'. You will learn MySQL fast, easy and fun. This makes the table a little slower to update, but also makes it easier to find corrupted tables. Any client can change the value of its In the C API, SET values are returned as In MariaDB, the default character set is latin1, and the default collation is latin1_swedish_ci (however this may differ in some distros, see for example Differences in MariaDB in Debian).Both character sets and collations can be specified from the server right down to the column level, as well as for client-server connections. When using EF Core migrations to manage your database schema, the following in your model's OnModelCreating method configures a SQL Server database to use a case-sensitive collation: Collations can also be defined on text columns, overriding the database default. This means that if you search with col_name LIKE 'a%' , you get all column values that start with A or a . retrieved: If you set a SET column to an unsupported If there is no default database, DATABASE() returns The four TEXT types are The character_set_results system variable indicates the character set in which the server returns query results to the client. careful with comparisons of the second type. For character set. binary, and values are sorted and compared To force a query to use case-sensitive or case-insensitive comparison, specify a collation explicitly via EF.Functions.Collate as detailed above. element, it does not matter what order the elements are listed value anywhere, even as a substring max_allowed_packet VARCHAR column. TINYTEXT, TEXT, this Manual, Integer Types (Exact Value) - INTEGER, INT, SMALLINT, TINYINT, set_col and parse the For information about character set and collation names, see Chapter 10, Character Sets, Collations, Unicode.. To see the available character sets and collations, use the SHOW CHARACTER A BLOB is a binary large object that can hold SET values result in an error. definition. However, quotation marks are necessary to specify a user_name string containing special mysql> SELECT COLLATION('abc'); -> 'utf8mb4_0900_ai_ci' mysql> SELECT COLLATION(_utf8mb4'abc'); -> 'utf8mb4_0900_ai_ci' mysql> SELECT COLLATION(_latin1'abc'); -> 'latin1_swedish_ci' Returns the default (current) database name as a string in the utf8mb3 character set. BLOB or TEXT column that Welcome to the MariaDB monitor. However, since case-sensitivity is culture-sensitive (e.g. select * from information_schema.tables where table_schema='databasename'; select * from information_schema.tables where table_name ='table_name', Threads_connected :, Threads_running :sleepsleep, ------------------------+----------------------------+, --------------------+-------------------+. optional. Getting Started. distinguish them from other strings, see Set root password, enter new password: # See Section11.3.1, String Data Type Syntax for mysql> CREATE TABLE `interval` (begin INT, end INT); Query OK, 0 rows affected (0.01 sec) Exception: A word that follows a period in a qualified name must be an identifier, so it need not be quoted even if it is reserved: mysql> CREATE TABLE mydb.interval (begin INT, end INT); Query OK, 0 rows affected (0.01 sec) Each character set has a default collation.For example, the default collations for utf8mb4 and latin1 are utf8mb4_0900_ai_ci and latin1_swedish_ci, respectively.The INFORMATION_SCHEMA CHARACTER_SETS table and the SHOW CHARACTER SET statement indicate the default collation for each character set. those data types (see SET ROLE Statement. This includes result data such as column values, and result metadata such as column names and error messages. SET values, the cast operation causes the If a generated column is updated explicitly, the only permitted value is DEFAULT. The trigger_event does not represent a literal type of SQL statement that activates the trigger so much as it represents a type of table operation. For example, both mysql To override this, provide explicit CHARACTER SET and COLLATE table options.. For LOAD DATA statements that include no CHARACTER SET clause, the server uses the character set You can use SET max_seeks_for_key=value as an alternative way to force MySQL to prefer key scans instead of table scans. , MySQL. See Section5.1.11, Server SQL Modes. numeric context, the value retrieved has bits set corresponding allocated once per column when the table is opened. MySQL Connector/ODBC defines BLOB values as Values in CHAR, VARCHAR, and TEXT columns are sorted and compared according to the character set collation assigned to the column. Similarly, you can regard a See Section 10.3.2, Server Character Set and Collation.. MEDIUMTEXT, and LONGTEXT. Server version: Advanced Edition (Commercial) For complete details about SET syntax, see Section 13.7.6.1, SET Syntax for Variable Assignment.For a description of the privilege requirements for setting and persisting system variables, see Section 5.1.9.1, System Variable Privileges. (Default: 'UTF8_GENERAL_CI') timezone: The timezone configured on the MySQL server. You will learn MySQL fast, easy and fun. Because BLOB and TEXT In .NET, string equality is case-sensitive by default: s1 == s2 performs an ordinal comparison that requires the strings to be identical. For For example, an INSERT trigger activates not only for INSERT statements but also LOAD DATA statements because both statements insert rows into a table. Specifies a default collation for the table. contain commas. strings. error. code rather than giving application users the client program. Welcome to the MySQL Tutorial website! limits. For example, the default server-level collation in SQL Server for the "English (United States)" machine locale is SQL_Latin1_General_CP1_CI_AS, which is a case-insensitive, accent-sensitive collation. set_col contains the of the data objects you are storing with the storage utf8mb4 is a superset of utf8mb3, so for an operation such as the following concatenation, the result has character set utf8mb4 and the collation of utf8mb4_col: . Here is an example that uses date functions. Japanese, Section11.3.1, String Data Type Syntax. represented internally by a separately allocated object. The following query selects all rows with a date_col value from within the last 30 days: . This allows multiple indexes to be defined on the same column, speeding up operations with different collations (e.g. FIND_IN_SET() function or the Sqlite, PostgreSQL), others are case-insensitive (SQL Server, MySQL). MEDIUMINT, BIGINT, Fixed-Point Types (Exact Value) - DECIMAL, NUMERIC, Floating-Point Types (Approximate Value) - FLOAT, DOUBLE, Automatic Initialization and Updating for TIMESTAMP and DATETIME, Using Data Types from Other Database Engines, 8.0 For one thing, EF Core does know not which case-sensitive or case-insensitive collation should be used. This is The second looks for an exact match. TEXT columns, you must specify an index Suffixes for specifying a value multiplier can be used when setting a variable at server startup, but not to set the value with 'd,a', 'a,d,d', character_set_client character_set_connection character_set_database character_set_results character_set_server Japanese, 5.6 For truncation of nonspace have the same maximum lengths and storage requirements. both case-sensitive and case-insensitive comparisons). MEMORY storage engine does not support Db characterset: latin1 BLOB or TEXT columns Set this to 1 if you want MySQL to maintain a live checksum for all rows (that is, a checksum that MySQL updates automatically as the table changes). You can discuss example, if a table contains 'a', an attempt TEXT columns in the result of a query Japanese, Section11.7, Data Type Storage Requirements, Section8.4.4, Internal Temporary Table Use in MySQL, Section4.5.1, mysql The MySQL Command-Line Client, Section4.5.4, mysqldump A Database Backup Program, Section12.8, String Functions and Operators. Forums (http://forums.mysql.com/). column as a VARBINARY column that SELECT CONCAT(utf8mb3_col, utf8mb4_col); Similarly, the following comparison in the WHERE clause works according to the collation of utf8mb4_col: With this additional parameter, startup or runtime. Two different character sets cannot have the same collation. For information about using result set metadata to MySQL Connector/ODBC defines BLOB values as LONGVARBINARY and TEXT values as LONGVARCHAR. similar, but not the same: It finds rows where mysql: http://bjlfp.blog.163.com/blog/static/773684612012298455765/ Text processing in databases can be complex, and requires more user attention than one would suspect. specified as SET('a','b','c','d'), the SHOW COLLATION Statement. low-order bit of the stored value corresponding to the first set See Section 5.1.1, Configuring the Server.. For functions that operate on string positions, the first position is numbered 1. This can be accomplished by explicitly specifying a collation within the query itself: This generates a COLLATE clause in the SQL query, which applies a case-sensitive collation regardless of the collation defined at the column or database level: Indexes are one of the most important factors in database performance - a query that runs efficiently with an index can grind to a halt without that index. assigned a character set and collation. mode. Trailing spaces are automatically deleted from It packs 9 digits into 4 bytes. The default character set and collation are utf8mb4 and utf8mb4_0900_ai_ci, so nonbinary string comparisons are case-insensitive by default. character set and collation, and comparison and sorting are Server characterset: latin1 information about that option, see Section4.5.1, mysql The MySQL Command-Line Client. The four BLOB show full columns from tablename; 1. C API Basic Data Structures. In most respects, you can regard a BLOB Within the mysql client, binary strings specified at table creation time. This can be useful if certain columns need to be case-insensitive, while the rest of the database needs to be case-sensitive. [root@mini, none): # root(root) The following statements also are permitted: The first of these statements looks for values containing the SET NAMES 'charset_name' [COLLATE 'collation_name'], MySQLCharacter Set Support: http://dev.mysql.com/doc/refman/5.6/en/charset.html TEXT columns. SET values are sorted numerically. (,). 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