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Remove FAQ mention of DROP column.

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This commit is contained in:
Bruce Momjian
2005-02-01 01:41:37 +00:00
parent 25deba3141
commit 2ccf79a6a1
2 changed files with 12 additions and 35 deletions
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doc/FAQ
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@ -1,7 +1,7 @@
Frequently Asked Questions (FAQ) for PostgreSQL
Last updated: Mon Jan 31 20:35:58 EST 2005
Last updated: Mon Jan 31 20:41:21 EST 2005
Current maintainer: Bruce Momjian (pgman@candle.pha.pa.us)
@ -51,7 +51,7 @@
4.1) How do I SELECT only the first few rows of a query? A random row?
4.2) How do I find out what tables, indexes, databases, and users are
defined? How do I see the queries used by psql to display them?
4.3) How do you remove a column from a table, or change its data type?
4.3) How do you change a column's data type?
4.4) What is the maximum size for a row, a table, and a database?
4.5) How much database disk space is required to store data from a
typical text file?
@ -491,25 +491,16 @@
query to get information about the database.
There are also system tables beginning with pg_ that describe these
too. Use psql -l will list all databases.
too.
Use psql -l will list all databases.
Also try the file pgsql/src/tutorial/syscat.source. It illustrates
many of the SELECTs needed to get information from the database system
tables.
4.3) How do you remove a column from a table, or change its data type?
4.3) How do you change a column's data type?
DROP COLUMN functionality was added in release 7.3 with ALTER TABLE
DROP COLUMN. In earlier versions, you can do this:
BEGIN;
LOCK TABLE old_table;
SELECT ... -- select all columns but the one you want to remove
INTO TABLE new_table
FROM old_table;
DROP TABLE old_table;
ALTER TABLE new_table RENAME TO old_table;
COMMIT;
Changing the data type of a column can be done easily in 8.0 and later
with ALTER TABLE ALTER COLUMN TYPE.