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learning_grsql
Posting Yak Master
230 Posts |
Posted - 2012-09-23 : 09:20:13
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hi,I just started learning dynamic sql from free online sources. I'm confused with the multiple quotes on those examples.Is there any logic behind those quotes?Here is one example :DECLARE @sqlCommand varchar(1000)DECLARE @columnList varchar(75)DECLARE @city varchar(75)SET @columnList = 'CustomerID, ContactName, City'SET @city = '''London'''SET @sqlCommand = 'SELECT ' + @columnList + ' FROM customers WHERE City = ' + @cityEXEC (@sqlCommand) Why have they put three quotes in London? |
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bitsmed
Aged Yak Warrior
545 Posts |
Posted - 2012-09-23 : 10:11:03
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quote: Originally posted by learning_grsql hi,I just started learning dynamic sql from free online sources. I'm confused with the multiple quotes on those examples.Is there any logic behind those quotes?Here is one example :DECLARE @sqlCommand varchar(1000)DECLARE @columnList varchar(75)DECLARE @city varchar(75)SET @columnList = 'CustomerID, ContactName, City'SET @city = '''London'''SET @sqlCommand = 'SELECT ' + @columnList + ' FROM customers WHERE City = ' + @cityEXEC (@sqlCommand) Why have they put three quotes in London?
When inside the string definition, two single quotes will convert to one single quote.Lets say you want a string to hold the value I am a sql wiz, you'd just type:SET @description='I am a sql wiz'Now, if you want the string to hold I'm a sql wiz, you'd type:SET @description='I''m a sql wiz'In the example above:Red quotes are start/stop quotes for a given string.Green quotes are inside the given string, and will thus convert to a single quote.So in essence, the city variable in your example, is set to 'London' in order for the select statement to work, as you would write:SELECT CustomerID, ContactName, City FROM customers WHERE City = 'London'Hope that you understand, if not let me know, and I'll explain another way. |
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visakh16
Very Important crosS Applying yaK Herder
52326 Posts |
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learning_grsql
Posting Yak Master
230 Posts |
Posted - 2012-09-24 : 03:33:42
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Many Thanks bitsmed and Visakh.Now I feel like I have understood quotes completely. |
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visakh16
Very Important crosS Applying yaK Herder
52326 Posts |
Posted - 2012-09-24 : 13:04:28
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welcome------------------------------------------------------------------------------------------------------SQL Server MVPhttp://visakhm.blogspot.com/ |
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