Adrian Klaver <adrian.klaver@aklaver.com> writes:
> On 03/02/2018 04:36 PM, Dale Seaburg wrote:
>> To finish off the WHERE clause, I need to look at the first 2 letters,
>> like "D:". My question is how do I specify in the WHERE clause, to look
>> at the first 2 characters in the Image_Filename column? What is the
>> correct SQL syntax for looking at just a portion of a column?
> SELECT "Image_Filename" FROM "Instruments" WHERE "ImageFilename" LIKE 'D:%';
Another way is to use the substring() function:
SELECT "Image_Filename" FROM "Instruments"
WHERE substring("ImageFilename", 1, 2) = 'D:';
or if you want to use the SQL committee's COBOLish syntax:
SELECT "Image_Filename" FROM "Instruments"
WHERE substring("ImageFilename" FROM 1 FOR 2) = 'D:';
Depending on what you're doing, either the pattern-match way or the
substring way might be more convenient. The performance implications
are different too, though that won't matter to you unless you're dealing
with so much data that you want to create a specialized index to make
queries of this form faster.
regards, tom lane
