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Mention ALTER COLUMN TYPE in FAQ.

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Bruce Momjian
2005-01-17 03:02:56 +00:00
parent 5be1e13dd1
commit 56d982b7d4
2 changed files with 12 additions and 6 deletions
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doc/FAQ
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Frequently Asked Questions (FAQ) for PostgreSQL Frequently Asked Questions (FAQ) for PostgreSQL
Last updated: Sun Jan 16 21:40:18 EST 2005 Last updated: Sun Jan 16 22:01:06 EST 2005
Current maintainer: Bruce Momjian (pgman@candle.pha.pa.us) Current maintainer: Bruce Momjian (pgman@candle.pha.pa.us)
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ALTER TABLE new_table RENAME TO old_table; ALTER TABLE new_table RENAME TO old_table;
COMMIT; COMMIT;
To change the data type of a column, do this: Changing the data type of a column can be done easily in 8.0 and later
with ALTER TABLE ALTER COLUMN TYPE.
In earlier releases, do this:
BEGIN; BEGIN;
ALTER TABLE tab ADD COLUMN new_col new_data_type; ALTER TABLE tab ADD COLUMN new_col new_data_type;
UPDATE tab SET new_col = CAST(old_col AS new_data_type); UPDATE tab SET new_col = CAST(old_col AS new_data_type);

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doc/src/FAQ/FAQ.html
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alink="#0000ff"> alink="#0000ff">
<H1>Frequently Asked Questions (FAQ) for PostgreSQL</H1> <H1>Frequently Asked Questions (FAQ) for PostgreSQL</H1>
<P>Last updated: Sun Jan 16 21:40:18 EST 2005</P> <P>Last updated: Sun Jan 16 22:01:06 EST 2005</P>
<P>Current maintainer: Bruce Momjian (<A href= <P>Current maintainer: Bruce Momjian (<A href=
"mailto:pgman@candle.pha.pa.us">pgman@candle.pha.pa.us</A>)<BR> "mailto:pgman@candle.pha.pa.us">pgman@candle.pha.pa.us</A>)<BR>
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<H4><A name="4.4">4.4</A>) How do you remove a column from a <H4><A name="4.4">4.4</A>) How do you remove a column from a
table, or change its data type?</H4> table, or change its data type?</H4>
<P><SMALL>DROP COLUMN</SMALL> functionality was added in release 7.3 with <P><SMALL>DROP COLUMN</SMALL> functionality was added in release 7.3
<SMALL>ALTER TABLE DROP COLUMN</SMALL>. In earlier versions, with <SMALL>ALTER TABLE DROP COLUMN</SMALL>. In earlier versions,
you can do this:</P> you can do this:</P>
<PRE> <PRE>
BEGIN; BEGIN;
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COMMIT; COMMIT;
</PRE> </PRE>
<P>To change the data type of a column, do this:</P> <P>Changing the data type of a column can be done easily in 8.0
and later with <SMALL>ALTER TABLE ALTER COLUMN TYPE</SMALL>.
<P>In earlier releases, do this:</P>
<PRE> <PRE>
BEGIN; BEGIN;
ALTER TABLE tab ADD COLUMN new_col <i>new_data_type</i>; ALTER TABLE tab ADD COLUMN new_col <i>new_data_type</i>;