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Re: How to build a query

From: Mick <mickg01(at)verizon(dot)net>
To: pgsql-novice(at)postgresql(dot)org
Subject: Re: How to build a query
Date: 2012-01-21 00:54:27
Message-ID: 4F1A0CC3.8000204@verizon.net (view raw or flat)
Thread:
Lists: pgsql-novice
On 01/20/2012 06:20 PM, JORGE MALDONADO wrote:
> I have to build a query at run-time which will contain a WHERE clause. 
> There is a field in a table that has to be tested against several 
> values but I do not know in advance how many values exist. For example,
>
> SELECT fld1, fld2, fld3 FROM tblTable
> WHERE fld1 = value[1] OR fld1 = value[2] OR fld1 = value[3]
>
> value[] is an array that contains all of the possible values that fld1 
> may take but I do not know how many items such array has. A value of 
> -1 in the array position indicates that it will not be taken into 
> account. So, I need to traverse the whole array and include those 
> values different from -1 in the WHERE clause. I can do a FOR...NEXT 
> and concatenate the conditions getting only those values different 
> than -1 but I wonder if this is a good approach; the query might grow 
> depending on the number of valid values in the array. Please advice if 
> there is a better way to build my query.
>
> Respectfully,
> Jorge Maldonado
SELECT columns
FROM tables
WHERE column1 in (value1, value2, .... value_n);

Mickg

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