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MySQL 9.4 Reference Manual  / ...  / INFORMATION_SCHEMA Tables  / INFORMATION_SCHEMA InnoDB Tables  /  The INFORMATION_SCHEMA INNODB_COLUMNS Table

28.4.9 The INFORMATION_SCHEMA INNODB_COLUMNS Table

TheINNODB_COLUMNS table provides metadata aboutInnoDB table columns.

For related usage information and examples, seeSection 17.15.3, “InnoDB INFORMATION_SCHEMA Schema Object Tables”.

TheINNODB_COLUMNS table has these columns:

  • TABLE_ID

    An identifier representing the table associated with the column; the same value asINNODB_TABLES.TABLE_ID.

  • NAME

    The name of the column. These names can be uppercase or lowercase depending on thelower_case_table_names setting. There are no special system-reserved names for columns.

  • POS

    The ordinal position of the column within the table, starting from 0 and incrementing sequentially. When a column is dropped, the remaining columns are reordered so that the sequence has no gaps. ThePOS value for a virtual generated column encodes the column sequence number and ordinal position of the column. For more information, see thePOS column description inSection 28.4.29, “The INFORMATION_SCHEMA INNODB_VIRTUAL Table”.

  • MTYPE

    Stands for“main type”. A numeric identifier for the column type. 1 =VARCHAR, 2 =CHAR, 3 =FIXBINARY, 4 =BINARY, 5 =BLOB, 6 =INT, 7 =SYS_CHILD, 8 =SYS, 9 =FLOAT, 10 =DOUBLE, 11 =DECIMAL, 12 =VARMYSQL, 13 =MYSQL, 14 =GEOMETRY.

  • PRTYPE

    TheInnoDB“precise type”, a binary value with bits representing MySQL data type, character set code, and nullability.

  • LEN

    The column length, for example 4 forINT and 8 forBIGINT. For character columns in multibyte character sets, this length value is the maximum length in bytes needed to represent a definition such asVARCHAR(N); that is, it might be2*N,3*N, and so on depending on the character encoding.

  • HAS_DEFAULT

    A boolean value indicating whether a column that was added instantly usingALTER TABLE ... ADD COLUMN withALGORITHM=INSTANT has a default value. All columns added instantly have a default value, which makes this column an indicator of whether the column was added instantly.

  • DEFAULT_VALUE

    The initial default value of a column that was added instantly usingALTER TABLE ... ADD COLUMN withALGORITHM=INSTANT. If the default value isNULL or was not specified, this column reportsNULL. An explicitly specified non-NULL default value is shown in an internal binary format. Subsequent modifications of the column default value do not change the value reported by this column.

Example

mysql> SELECT * FROM INFORMATION_SCHEMA.INNODB_COLUMNS where TABLE_ID = 71\G*************************** 1. row ***************************     TABLE_ID: 71         NAME: col1          POS: 0        MTYPE: 6       PRTYPE: 1027          LEN: 4  HAS_DEFAULT: 0DEFAULT_VALUE: NULL*************************** 2. row ***************************     TABLE_ID: 71         NAME: col2          POS: 1        MTYPE: 2       PRTYPE: 524542          LEN: 10  HAS_DEFAULT: 0DEFAULT_VALUE: NULL*************************** 3. row ***************************     TABLE_ID: 71         NAME: col3          POS: 2        MTYPE: 1       PRTYPE: 524303          LEN: 10  HAS_DEFAULT: 0DEFAULT_VALUE: NULL

Notes

  • You must have thePROCESS privilege to query this table.

  • Use theINFORMATION_SCHEMACOLUMNS table or theSHOW COLUMNS statement to view additional information about the columns of this table, including data types and default values.