Difference between revisions of "String over columns"

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Line 18: Line 18:
 
  OR ceilingcolor = 'YELLOW'
 
  OR ceilingcolor = 'YELLOW'
 
  OR wallcolor = 'YELLOW'
 
  OR wallcolor = 'YELLOW'
<p>Using OR increases the chances for careless mistakes instead
+
<p>Using <code>OR</code> increases the chances for careless mistakes instead
CONCAT could be used to make the query more efficient.</p>
+
<code>CONCAT</code> could be used to make the query more efficient.</p>
<p>To avoid problems make sure to add in separators and if a value cna be null
+
<p>To avoid problems make sure to add in separators and if a value can be null
make sure to use it is wrapped in COALESCE OR NVL for example:</p>
+
make sure to use it is wrapped in <code>COALESCE</code> or <code>NVL</code> for example:</p>
 
COALESCE(floorcolor,' ').
 
COALESCE(floorcolor,' ').
 
</div>
 
</div>
Line 27: Line 27:
 
WHERE CONCAT (':',floorcolor,':',ceilingcolor,':',wallcolor,':')
 
WHERE CONCAT (':',floorcolor,':',ceilingcolor,':',wallcolor,':')
 
LIKE '%:YELLOW:%'</source>
 
LIKE '%:YELLOW:%'</source>
<div class="ecomm e-mysql" style="display: none">Instead of COALESCE or NVL, IFNULL can be used.</div>
+
<div class="ecomm e-mysql" style="display: none">Instead of <code>COALESCE</code> or <code>NVL</code>, <code>IFNULL</code> can be used.</div>
<div class="ecomm e-sqlsever" style="display: none">Instead of COALESCE or NVL, IFNULL can be used.</div>
+
<div class="ecomm e-sqlserver" style="display: none">Instead of <code>COALESCE</code> or <code>NVL</code>, <code>IFNULL</code> can be used.</div>
 
</div>
 
</div>
 
{{Hacks Ref}}
 
{{Hacks Ref}}

Revision as of 14:38, 30 July 2012

Search for a string across columns

schema:scott
DROP TABLE bedrooms
 CREATE TABLE bedrooms(
  name VARCHAR(20),
  floorcolor VARCHAR(20),
  ceilingcolor VARCHAR(20),
  wallcolor VARCHAR(20));
INSERT INTO bedrooms VALUES ('Jim','RED','GREEN','YELLOW');
INSERT INTO bedrooms VALUES ('Bob','YELLOW','BLUE','BLACK');
INSERT INTO bedrooms VALUES ('Allan','BLUE','PINK','BLACK');
INSERT INTO bedrooms VALUES ('George','BLUE','GREEN','OAK');
SELECT name FROM bedrooms
WHERE floorcolor = 'YELLOW'
OR ceilingcolor = 'YELLOW'
OR wallcolor = 'YELLOW'

Using OR increases the chances for careless mistakes instead CONCAT could be used to make the query more efficient.

To avoid problems make sure to add in separators and if a value can be null make sure to use it is wrapped in COALESCE or NVL for example:

COALESCE(floorcolor,' ').

SELECT name FROM bedrooms
WHERE CONCAT (':',floorcolor,':',ceilingcolor,':',wallcolor,':')
LIKE '%:YELLOW:%'
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