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 |
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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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