Checking multiple columns for one value

Efficiency with the IN predicate

Transform messy strings of OR conditions into a neat, readable inquiry using the IN predicate. Here's an illustration of this in action:

-- If 'value' is the needle, let's see in which haystack column it's hiding
SELECT *
FROM your_table
WHERE 'value' IN (column1, column2, column3);


CONCATENATION: finding values in combined columns

Values lost somewhere within merged columns? No worries, the concatenation of columns has got your back.

-- Joined columns to form a super-column, seeking 'value' in it
SELECT *
FROM your_table
WHERE CONCAT(column1, column2, column3) LIKE '%value%';


Ensure uniformity of data type by casting numeric columns as VARCHAR:

-- Data type uniformity achieved. Let's find that sneaky 'value'
SELECT *
FROM your_table
WHERE CONCAT(CAST(column1 AS VARCHAR), CAST(column2 AS VARCHAR), column3) LIKE '%value%';


Powering up with subqueries

Subqueries partnering with the IN operator can bring both efficiency and readability to the fore:

-- Requesting help from the subquery squad to locate 'value'
SELECT *
FROM your_table t1
WHERE EXISTS (
    SELECT 1
    FROM (
        SELECT column1
        UNION ALL SELECT column2
        UNION ALL SELECT column3
    ) AS subquery(column_value)
    WHERE t1.id = subquery.column_value
);


Make it work and make it fast

The IN operator brings the gift of readability, but be sure to keep track of performance. Adding indexes on searched columns can give a great speed boost.

Fitting your needs

Adapt these techniques according to your specific scenario:

1. With derived tables or intricate joins, revert to IN with subqueries.
2. For variable column checks, roll out dynamic SQL.
3. To induce varied logic or simultaneous conditions, opt for CASE statements.
4. When playing with concatenated values, cast data types accordingly to dodge surprise outcomes.

Prioritize readability and maintainability

Intricate code might be fun, but don't forget the importance of readability and maintainability. Make a future developer's job (or future you) a little easier with clear, understandable queries.