Difference between revisions of "COALESCE"
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COALESCE(x,y,z) = x if x is not NULL | COALESCE(x,y,z) = x if x is not NULL | ||
COALESCE(x,y,z) = y if x is NULL and y is not NULL | COALESCE(x,y,z) = y if x is NULL and y is not NULL | ||
| − | COALESCE( | + | COALESCE(x,y,z) = z if x and y are NULL but z is not NULL |
COALESCE(x,y,z) = NULL if x and y and z are all NULL | COALESCE(x,y,z) = NULL if x and y and z are all NULL | ||
</pre> | </pre> | ||
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<li>[[NVL |NVL function]]</li> | <li>[[NVL |NVL function]]</li> | ||
</ul> | </ul> | ||
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| + | {{Languages}} | ||
Latest revision as of 10:04, 1 October 2012
| COALESCE(f1, f2) | ||
|---|---|---|
| Engine | OK | Alternative |
| ingres | Yes | |
| mysql | Yes | IFNULL(f1, f2) |
| oracle | Yes | NVL(f1, f2) |
| postgres | Yes | |
| sqlserver | Yes | |
COALESCE
COALESCE takes any number of arguments and returns the first value that is not null.
COALESCE(x,y,z) = x if x is not NULL COALESCE(x,y,z) = y if x is NULL and y is not NULL COALESCE(x,y,z) = z if x and y are NULL but z is not NULL COALESCE(x,y,z) = NULL if x and y and z are all NULL
schema:gisq
COALESCE can be useful when you want to replace a NULL value with some other value. In this example you show the name of the party for each MSP that has a party. For the MSP with no party (such as Canavan, Dennis) you show the string None.
SELECT name, party ,COALESCE(party,'None') AS aff FROM gisq.msp WHERE name LIKE 'C%'
SELECT name, party ,COALESCE(party,'None') AS aff FROM msp WHERE name LIKE 'C%'
See also
| Language: | English • Deutsch |
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