25.39.8 The INFORMATION_SCHEMA INNODB_COLUMNS Table

TABLE_ID

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

NAME

The name of the column. These names can be uppercase or lowercase depending on the lower_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. The POS value for a virtual generated column encodes the column sequence number and ordinal position of the column. For more information, see the POS column description in Section 25.39.30, “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

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

LEN

The column length, for example 4 for INT and 8 for BIGINT. For character columns in multibyte character sets, this length value is the maximum length in bytes needed to represent a definition such as VARCHAR(N); that is, it might be 2*N, 3*N, and so on depending on the character encoding.

HAS_DEFAULT

A boolean value indicating whether a column that was added instantly using ALTER TABLE ... ADD COLUMN with ALGORITHM=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 using ALTER TABLE ... ADD COLUMN with ALGORITHM=INSTANT. If the default value is NULL or was not specified, this column reports NULL. 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.

You must have the PROCESS privilege to query this table.

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