SQL CREATE ALTER DROP TABLE: Difference between revisions
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==Add/Remove a Constraint== | ==Add/Remove a Constraint== | ||
===<tt>NOT NULL</tt>=== | ===<tt>NOT NULL</tt>=== | ||
<syntaxhighlight lang='sql'> | |||
ALTER TABLE sometable ALTER COLUMN somecolumn SET NOT NULL; | |||
</syntaxhighlight> | |||
<syntaxhighlight lang='sql'> | |||
ALTER TABLE sometable ALTER COLUMN somecolumn DROP NOT NULL; | |||
</syntaxhighlight> | |||
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===Primary Key=== | |||
=== | |||
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Revision as of 19:29, 23 May 2024
Internal
Overview
CREATE
CREATE [TEMPORARY] TABLE person
( id smallint,
name varchar(30) NOT NULL,
CONSTRAINT pk_person PRIMARY KEY (id)
);
If the TEMPORARY
keyword is used, the created table will be temporary instead of permanent.
ALTER
ALTER TABLE person [...]
Add/Remove a Column
ALTER TABLE person ADD COLUMN birthday DATE;
ALTER TABLE person DROP COLUMN birthday;
Add/Remove a Constraint
NOT NULL
ALTER TABLE sometable ALTER COLUMN somecolumn SET NOT NULL;
ALTER TABLE sometable ALTER COLUMN somecolumn DROP NOT NULL;
Primary Key
DROP
DROP TABLE person [...]