| MySQL: Primar y key, index, unique
what is what? |
dr_paul
msg:3605170 | 11:52 am on Mar 19, 2008 (gmt 0) |
In MySQL - what is a "primary keys"? Is it one column in a table?
Can it be more than one column?
Is it the same as an Index?
Does a table HAVE to have a primary key?
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badone
msg:3609012 | 9:04 am on Mar 24, 2008 (gmt 0) |
| Is it one column in a table? |
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It can be one or more. | Is it the same as an Index? |
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No, a primary key uniquely identifies each individual row in a table. An index improves the speed of operations on a table, it can also be on one or more columns. | Does a table HAVE to have a primary key? |
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No, but it is good practice IMHO. Cheers,
badone
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dr_paul
msg:3609017 | 9:20 am on Mar 24, 2008 (gmt 0) |
Thanks for posting, bad one - and thanks for your straight answers. Kudos.
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