Can I use OR instead of AND?

Yes—replace AND with OR when any condition may be true, but use parentheses to control precedence.

What should I do when a parameter can be NULL?

Either omit that predicate from the dynamic query or use "IS NULL" explicitly, e.g., "AND (COL5 = ? OR COL5 IS NULL)".

Is there a limit to the number of conditions in a WHERE clause?

SQL standards impose no practical limit; the constraint is memory and parser capacity, which are far beyond eight conditions.

2026-09-04 · Q&A guide

How to Combine Multiple WHERE Clauses in a Single SQL Query

Learn to filter rows with eight conditions using one WHERE clause and logical operators in SQL.

The purpose of a single WHERE clause

SQL allows only one WHERE keyword per SELECT statement. All column filters are expressed inside that clause, joined by logical operators such as AND or OR. This design keeps the query grammar simple and lets the optimizer evaluate the whole predicate as a unit.

Chaining conditions with AND

When every condition must be true, connect them with AND. The order of the predicates does not affect the result, but it can influence performance because the optimizer may reorder them based on statistics.

SELECT *
FROM Table
WHERE ID   = ?
  AND COL2 = ?
  AND COL3 = ?
  AND COL4 = ?
  AND COL5 = ?
  AND COL6 = ?
  AND COL7 = ?
  AND COL8 = ?;

Using prepared statements and named parameters

Most database drivers support placeholders, which protect against injection and let the engine reuse execution plans. Named parameters improve readability, especially with many columns.

Example with named placeholders:

SELECT *
FROM Table
WHERE ID   = :id
  AND COL2 = :col2
  AND COL3 = :col3
  AND COL4 = :col4
  AND COL5 = :col5
  AND COL6 = :col6
  AND COL7 = :col7
  AND COL8 = :col8;

Building dynamic WHERE clauses

If some filters are optional, construct the query programmatically. Start with the base SELECT and append "AND column = ?" only when the corresponding value is supplied. This avoids hard‑coding "IS NULL" checks and keeps the SQL clean.

Common pitfalls to avoid

Do not repeat the WHERE keyword; doing so creates a syntax error. Remember that mixing AND and OR without parentheses changes the logical grouping. Also, ensure the data types of the parameters match the column definitions to prevent implicit conversions.

Takeaway: Place all eight predicates inside one WHERE clause, separated by AND (or OR) operators.