![]() In this tutorial, we have introduced you to the MySQL CHAR data type and its features. Duplicate entry 'N' for key 'uidx_status' Code language: JavaScript ( javascript ) VALUES( 'N ') Code language: SQL (Structured Query Language) ( sql ) Error Code: 1062. Third, insert the following value will cause a duplicate key error. ![]() VALUES( 'N') Code language: SQL (Structured Query Language) ( sql ) ![]() Second, insert a new row into the mysql_char_test table. ON mysql_char_test( status) Code language: SQL (Structured Query Language) ( sql ) If the CHAR column has a UNIQUE index and you insert a value that is different from an existing value in a number of trailing spaces, MySQL will reject the changes because of duplicate-key error.įirst, create a unique index for the status column of the mysql_char_test table. WHERE status = ' Y' Code language: SQL (Structured Query Language) ( sql ) MySQL CHAR and UNIQUE index To match with the ‘ Y ‘, we need to remove the trailing space as follows: SELECT * MySQL returns no row because it does not consider the trailing space. WHERE status = 'Y' Code language: SQL (Structured Query Language) ( sql ) However, when we execute the following query: SELECT * In the previous example, we stored the value Y with both leading and trailing spaces. Notice that the LIKE operator does consider the trailing spaces when you do pattern matching with CHAR values. MySQL does not consider trailing spaces when comparing CHAR values using the comparison operator such as =,, >, <, etc. ![]() When storing or comparing the CHAR values, MySQL uses the character set collation assigned to the column. Mysql_char_test Code language: SQL (Structured Query Language) ( sql ) Comparing MySQL CHAR values VALUES( ' Y ') Code language: SQL (Structured Query Language) ( sql )įinally, query the inserted values, you will see that MySQL removes the trailing spaces. Mysql_char_test Code language: SQL (Structured Query Language) ( sql )įourth, inserts a CHAR value with the leading and trailing spaces. Third, use the length function to get the length of each CHAR value. VALUES( 'Yes'),( 'No') Code language: SQL (Structured Query Language) ( sql ) Second, insert two rows into the mysql_char_test table. The data type of the status column is CHAR. ![]() ) Code language: SQL (Structured Query Language) ( sql ) Note that MySQL will not remove the trailing spaces if you enable the PAD_CHAR_TO_FULL_LENGTH SQL mode.įirst, creates a table with a CHAR column. When you query the CHAR value, MySQL removes the trailing spaces. When you store a CHAR value, MySQL pads its value with spaces to the length that you declared. The length of the CHAR data type can be any value from 0 to 255. You’ll get a better performance in comparison with VARCHAR in this case. If the data that you want to store is a fixed size, then you should use the CHAR data type. For example, CHAR(20) can hold up to 20 characters. You often declare the CHAR type with a length that specifies the maximum number of characters that you want to store. The CHAR data type is a fixed-length character type in MySQL. Summary: in this tutorial, you will learn about MySQL CHAR data type and how to apply it in your database table design. ![]()
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