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cwtriguns2002
Constraint Violating Yak Guru
272 Posts |
 Posted - 2007-03-16 : 03:05:50
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| Hi all. I think its a silly question to ask. What is better to use? I mean in terms of performance.c.* or c.field1, c.field2, c.field3, c.lastfield..... ?thanks-Ron- |
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AndrewMurphy
Master Smack Fu Yak Hacker
2916 Posts |
Posted - 2007-03-16 : 06:54:07
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| not silly....answer just not necessarily obvious.c.field1, c.field2, c.field3, etc...is betterc.*....will require a data lookup...where as 1st form may be satisfied by a covering index.Also...better practice to 'know' what fields are returned by SQL code, rather than leave it up to chance by dint of actions of some future DBA....ie adding in 1 extra column or worse deleting 1 column (without checking all instances of where it's used!)Also if the extra column includes TEXT/image...then performance will go way west!!!"Short-cut Scripts" are available turn C.* into c.field1, c.field2, etc...search here for references to same....may be posted on some of the related blogs. |
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cwtriguns2002
Constraint Violating Yak Guru
272 Posts |
Posted - 2007-03-16 : 08:02:08
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| thanks Andrew Murphy for the reply and explanation. Now i get it.-Ron- |
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silly question