information_schema.columns.is_nullable

mysql

type: VARCHAR NOT NULL
5.7-8

mariadb

type: NULL
Note:
Whether the column can contain NULLs.
© 2022 MariaDB
5.1-10.8
type: VARCHAR NOT NULL
Note:
Whether the column can contain NULLs.
© 2022 MariaDB
10.2-10.7

tidb

type: VARCHAR(3) NULL
Note:
Whether the column is nullable. If the column can store null values, this value is YES; otherwise, it is NO.
© 2022 PingCAP
4-6.1

postgres

type: YES_OR_NO NULL
Note:
YES if the column is possibly nullable, NO if it is known not nullable. A not-null constraint is one way a column can be known not nullable, but there can be others.
© 1996-2022 The PostgreSQL Global Development Group
10-15
type: CHARACTER_DATA
Note:
YES if the column is possibly nullable, NO if it is known not nullable. A not-null constraint is one way a column can be known not nullable, but there can be others.
© 1996-2022 The PostgreSQL Global Development Group
8.3-9.6
Note:
YES if the column is possibly nullable, NO if it is known not nullable. A not-null constraint is one way a column can be known not nullable, but there may be others.
© 1996-2022 The PostgreSQL Global Development Group
7.4-8.2

cockroachdb

type: unknown
Note:
YES if the column accepts NULL values; NO if it doesn't (e.g., it has the NOT NULL constraint).
© 2022 CockroachDB
2-21.2
Note:
YES if the column accepts NULL values; NO if it doesn't (e.g., it has the Not Null constraint).
© 2022 CockroachDB
1-1.1

mssql

type: VARCHAR(3) NULL
Note:
Nullability of the column. If this column allows for NULL, this column returns YES. Otherwise, NO is returned.
© Microsoft 2022
aps-pdw-2016-sql-server-ver15