the scope of theWHEREclause includes theUPDATEandDELETEstatements. TheWHEREclause is indispensable for quality work with MySQL databases. That’s why the current article will deal with this clause and explore its distinguishing features in-depth. ...
In SQL, in order to EXCLUDE certain rows from being returned by a SELECT query, we use some restricting or excluding conditions based on some criteria. EXCLUDE conditions in SQL usually appear in the WHERE clause of the statement or in the HAVING clause of an aggregate query. Some commonly ...
it moves to the next expression, evaluating until a non-null value is obtained or reaches the end of the chain. This nesting helps in creating backup mechanisms or default values for columns or expressions in SQL queries, ensuring
User-defined functions (UDFs):SQL allows you to create user-defined functions, which are custom functions that can be used in SQL queries. UDFs enable you to encapsulate complex data cleaning operations into reusable functions, making your cleaning tasks more modular and maintainable. Temporal t...
Note: unless otherwise stated, all queries below will be written against the “MyTestDB” database. Option 1. Creating our test database with the SSMS GUI Open SSMS and connect to your SQL Server instance. Once you are there, look in the “Object Explorer” and right click on “Databases...
EXISTS is used as an operator in the WHERE clause of a SQL query to check if the result set obtained from the correlated nested subquery is empty or not. If the result set is empty, EXISTS returns FALSE. Otherwise, it returns TRUE. ...
ORis used to combine two or more conditions in a where clause. The results have to match at least one of the conditions specified. SELECT * FROM table_name WHERE condition_1 OR condition_2; SELECT DISTINCTreturns unique values in the specified column(s). ...
Using an EXISTS function call in a WHERE clause is probably the most common use case. The function will work exactly the same as in each earlier example, but there is one noticeable change. The subquery will almost always reference a column in a table that is otherwise out of the scope ...
SQL WHERE Clause: SELECT column1, column2….columnN FROM table_name WHERE CONDITION; SQL AND/OR Clause: SELECT column1, column2….columnN FROM table_name WHERE CONDITION-1 {AND|OR} CONDITION-2; SQL IN Clause: SELECT column1, column2….columnN FROM table_name WHERE column_name IN (val...
In this part of the SQL Server query execution plans series, we describe the examples with the WHERE clause, showing how indexes affect query execution plans and costs