SQL Constraints: Difference between revisions
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=<tt>NOT NULL</tt> Constraint= | =<tt>NOT NULL</tt> Constraint= | ||
<syntaxhighlight lang='sql'> | |||
CREATE TABLE ... | |||
( ... | |||
somecolumn varchar(30) NOT NULL, | |||
... | |||
); | |||
</syntaxhighlight> | |||
Also see: {{Internal|SQL#SQL_NULL|<tt>NULL</tt>}} | Also see: {{Internal|SQL#SQL_NULL|<tt>NULL</tt>}} | ||
Revision as of 00:02, 23 May 2024
Internal
Overview
NOT NULL Constraint
CREATE TABLE ...
( ...
somecolumn varchar(30) NOT NULL,
...
);
Also see:
Primary Key Constraint
CREATE TABLE ...
( ...
CONSTRAINT pk_someconstraint PRIMARY KEY (somecolumn)
);
Check Constraint
CREATE TABLE ...
( ...
eye_color CHAR(2) CHECK (eye_color IN ('BR', 'BL', 'GR')),
...
);