Question

Say I have a table with three columns primaryNum, secondaryNum, chosenNum. primarynum and secondaryNum are both number values but chosenNum’s value can either be “primaryNum”, “secondaryNum”, or “both”.

The chosenNum field is a column that gives me the option to search for a number in a particular field.

For example: I might want to try to find all rows with the value 10 in the column that is stored in chosenNum. If the value of chosenNum is “both” then the row would be returned if either column (primaryNum, secondaryNum) had a value of 10.

What might my select statement look like?

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It might be a better scenario if I say I would like to do a select statement like:

SELECT * FROM aTable WHERE (SELECT bVal FROM bTable WHERE aVal = @varField ) = 0;

Where @varField is the value of the value in the field with the label stored in chosenNum or either field if chosenNum = “both”

This would result in me getting back rows with id 1,2,3,4,6,7,14,15,16,19,20,21,23,24,27

Table A: Create

CREATE  TABLE `test`.`aTable` (
  `id` INT NOT NULL AUTO_INCREMENT ,
  `primaryNum` INT NULL ,
  `secondaryNum` INT NULL ,
  `chosenNum` CHAR(12) NULL ,
  PRIMARY KEY (`id`) );

Table B: Create

CREATE  TABLE `test`.`bTable` (
  `aVal` INT NULL ,
  `bVal` INT NULL );

Table A: Data

INSERT INTO test.aTable VALUES (1,8,7,'secondaryNum'),(2,2,9,'secondaryNum'),(3,7,9,'both'),(4,5,1,'both'),(5,10,3,'secondaryNum'),(6,10,6,'both'),(7,7,8,'both'),(8,10,2,'primaryNum'),(9,2,1,'secondaryNum'),(10,7,2,'secondaryNum'),(11,2,2,'secondaryNum'),(12,5,1,'secondaryNum'),(13,1,6,'primaryNum'),(14,6,6,'both'),(15,4,9,'both'),(16,9,7,'primaryNum'),(17,8,3,'secondaryNum'),(18,10,7,'primaryNum'),(19,8,5,'secondaryNum'),(20,1,7,'both'),(21,7,9,'both'),(22,8,3,'primaryNum'),(23,6,2,'primaryNum'),(24,5,7,'both'),(25,2,1,'both'),(26,5,2,'secondaryNum'),(27,7,8,'primaryNum');

Table B: Data

INSERT INTO test.bTable VALUES (1,1),(2,1),(3,1),(4,1),(5,0),(6,0),(7,0),(8,1),(9,0),(10,1);

Answer 1

You can do something like this:

select * 
from MyTable
where (chosenNum in ('both', 'primaryNum') and primaryNum = 10)
    or (chosenNum in ('both', 'secondaryNum') and secondaryNum = 10)