How many where clause can be there in sql query?

Answer 1

In simple sql query (such as SELECT * FROM table_name WHERE condition...) we can use only one WHERE clause, but WHERE clause is not only used in simple SELECT statement, it is also used in complex queries, subqueries and etc.

For more information you can see following link:
https://docs.microsoft.com/en-us/sql/t-sql/queries/where-transact-sql

Answer 2

WHERE clause is used only once after SELECT statement generally but can be used with different and multiple set of conditions