IF statement with dynamic code

Question

3.00/5 (1 vote)

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hello,

i have a table

.....|Value|Operation|
_____|_____|_________|

.....| 001 | >= |
.....| 009 | <= |

It is possibile create a dynamic if?

example

SQL

DECLARE @myvar
SET @myvar ='070'


DECLARE @operation
DECLARE @Value
SELECT @operation = operation from mytable
SELECT @value = value from mytable

SQL

IF @myvar + @operation + @Value

thank you in advance

What I have tried:

i have tried to concatenate my variable but i fear tha is not possibile

Posted 2-Aug-16 0:58am

Member 10766684

Updated 2-Aug-16 12:04pm

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Comments

[no name] 2-Aug-16 7:29am

Could you send full condition formate?

Tomas Takac 2-Aug-16 8:13am

It is possible build and run SQL on the fly - depends on what you are trying to do. So post all your relevant code and explain where is the problem. But if it's your fear what is holding you back then this is not the right forum.

Member 10766684 2-Aug-16 9:34am

this is my code

BEGIN

DECLARE db_cursor CURSOR FOR
SELECT Position, Lenght,Value, Operation
FROM dbo.RulesStringLabel
where Custom = '0'

OPEN db_cursor
FETCH NEXT FROM db_cursor INTO @Position, @Lenght, @Value, @Operation

WHILE @@FETCH_STATUS = 0
BEGIN

SELECT @ValueCheck = SUBSTRING (@Label, @Position, @Lenght)
SELECT @OperationString = @Operation +' '+@Value

IF @ValueCheck + @OperationString

FETCH NEXT FROM db_cursor INTO @Position, @Lenght, @Value, @Operation
END

CLOSE db_cursor
DEALLOCATE db_cursor

END

Member 10766684 2-Aug-16 9:36am

My problem is on if statement, i cant translate the operator...

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RossMW · Answer 1 · 2016-08-02T12:04:00

See the small example below.

SQL

Declare @A nvarchar(100)
Declare @S nvarchar(100)
Declare @T nvarchar(10)

Select @T = '1 '
Select @A = ' = 2'
Select @S = 'if ' + @T +  @A + ' begin Select * from Table where SomeField = '''xx''' end'
Select @S --Display resultant SQL Statement only
EXECUTE sp_executeSQL @S

The principle behind this is to create a string which is your SQL statement out of the conditions you have and then execute that SQL statement. (hopefully the if statement is not too long)

See sp_executesql (Transact-SQL)[^]

When creating the SQL statement be careful of single quotes as these need to be added in as required. I have added an example of this as well.

e.g. 'A' in a select statement will end up being become '''A'''.

See How to include a single quote in a sql query[^]

What you should end up with is a SQL statement as a large nvarchar or string that can be executed.