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. (that is, 70 number positions)įor both MySQL and Postgres, NUMERIC is an alias for the DECIMAL type.Summary: in this tutorial, you will learn about MySQL CHAR data type and how to apply it in your database table design. The DECIMAL type in MySQL is equivalent to DECIMAL in postgres, except that in postgres, the type does not impose an arbtrary limit on the precision, whereas in MySQL the maximum precision is (i believe) 70. The FLOAT type in MySQL should be equivalent to REAL in postgres (and REAL in SQLite too) (but indeed MySQL's BLOB types also map to that) I think the MySQL VARBINARY data type is best comparable to PG's BYTEA datatype. The BIT datatypes in MySQL and PG have roughly the same semantics, but in MySQL the maximum length of the BIT data type is 64 (bits) In SQLite, VARCHAR and CHAR map both to TEXT The actual length specifier is expressed in the number of characters, so if you have a multi-byte character set, you have to divide the maximum lenght by the maximum number of characters to get the theoretical maximum length specified for that characterset. In MySQL these types can have a maximum of a little less than 64kb, in pg 1Gb (bytes). Semantically, VARCHAR in MySQL and PG, and CHAR in MySQL and PG are the same, but in MySQL these types have a much shorter maximum length. I am missing INTEGER (alias INT) for MySQL. Postgres also has a BIGSERIAL type, which is the same as SERIAL but with a BIGINT type instead of an INT type. In postgres, the SERIAL datatype results in an INTEGER column, and this will about the same as MySQL's INTEGER PRIMARY KEY AUTO_INCREMENT This is roughly equivalent to BIGINT PRIMARY KEY AUTO_INCREMENT So apps may or may not be portable - at least it is no drop in replacement.įinally, for the last line in your tabl I think the SQLite phrase should read: INTEGER PRIMARY KEY AUTOINCREMENT It looks like the pg BOOLEAN type uses string literal notation. In MySQL, TRUE and FALSE map to 1 and 0 integer values. You may or may not be able to port apps depending on what they use as boolean literals. The MySQL BOOLEAN (alias BOOL, alias TINYINT(1) ) is not compatible with the pg boolean type. I would avoid it, but otherwise map it to INTEGER too. MEDIUMINT in MySQL is an odd duck (3 bytes). MySQL PostgreSQL SQLiteĬolumnname INT columnname SERIAL INTEGER PRIMARY Here is what I have so far, but I'm afraid it's not done and I need some people with more experience to help me finish any missing types. I am trying to find some way to relate column types across the the most used Databases: MySQL, PostgreSQL, and SQLite.
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