What is the WHERE clause used for?

The WHERE clause is used to filter records. It is used to extract only those records that fulfill a specified condition.

What is the example of WHERE clause?

Lets fetch the employee details where employee age is greater than 23 and salary is greater than 5000. For such query we have to use multiple conditions in where clause. Another multiple conditions example: Fetch the employee names, where either employee age is less than 20 or salary is less than 5000.

What is WHERE by clause in SQL?

Advertisements. The SQL WHERE clause is used to specify a condition while fetching the data from a single table or by joining with multiple tables. If the given condition is satisfied, then only it returns a specific value from the table.

What is specified in the WHERE clause?

The FROM clause specifies one or more tables to be queried. Use a comma and space between table names when specifying multiple tables. The WHERE clause selects only the rows in which the specified column contains the specified value. The value is enclosed in single quotes (for example, WHERE last_name=’Vader’ ).

Which operator is permitted in a WHERE clause?

The WHERE clause must have comparison operator to evaluate the condition. It can use function as one of the operand. Only one WHERE clause is allowed in a SELECT query.

What exactly is a clause?

Definition of clause

1 : a group of words containing a subject and predicate and functioning as a member of a complex (see complex entry 2 sense 1b(2)) or compound (see compound entry 2 sense 3b) sentence The sentence “When it rained they went inside” consists of two clauses: “when it rained” and “they went inside.”

WHERE clause is used for rows or columns?

The WHERE clause is used in the selection of rows according to given conditions whereas the HAVING clause is used in column operations and is applied to aggregated rows or groups. If GROUP BY is used then it is executed after the WHERE clause is executed in the query.

What does follow after the SQL WHERE clause?

The correct answer to the question “What does follow after the SQL WHERE clause” is option (B). Definition of the condition to be met for the rows to be returned.

Can we use 2 WHERE clause in SQL?

Example – Two Conditions in the WHERE Clause (OR Condition)

You can use the OR condition in the WHERE clause to test multiple conditions where the record is returned if any one of the conditions are met.

What is difference between HAVING clause and WHERE clause?

A HAVING clause is like a WHERE clause, but applies only to groups as a whole (that is, to the rows in the result set representing groups), whereas the WHERE clause applies to individual rows. A query can contain both a WHERE clause and a HAVING clause.

What is the difference between WHERE and GROUP BY?

WHERE is used to filter records before any groupings take place that is on single rows. GROUP BY aggregates/ groups the rows and returns the summary for each group. HAVING is used to filter values after they have been groups.

Can we use WHERE with GROUP BY?

Absolutely. It will result in filtering the records on your date range and then grouping it by each day where there is data.

Can I use WHERE and HAVING together?

We can combine the WHERE and HAVING clause together in a SELECT query. In this case, the WHERE clause is used first to filter individual rows. The rows are then grouped, perform aggregate calculations, and finally, the HAVING clause is used to filter the groups.

Which is faster WHERE or HAVING?

You can use HAVING but recommended you should use with GROUP BY . SQL Standard says that WHERE restricts the result set before returning rows and HAVING restricts the result set after bringing all the rows. So WHERE is faster.

Can you have a WHERE and HAVING in the same statement?

Yes, an SQL query can contain a WHERE and HAVING clause. You will use these together when you want to extract (or filter) rows for a group of data using a WHERE clause and apply a condition on the aggregate using the HAVING clause.

Does WHERE come before HAVING?

The where clause goes before the having and the group by . If you want to filter out records before the grouping the condition goes in the where clause, and if you want to filter out grouped records the condition goes in the having clause: select … from …

How is HAVING clause similar to WHERE clause How is HAVING clause different from WHERE clause explain with the help of examples of each?

Difference : A WHERE clause is used is filter records from a result. The filter occurs before airy groupings are made. A HAVING clause is used to filter values from a group.

WHERE conditions are applied before the HAVING conditions?

However, the HAVING clause applies the condition to the groups after the rows are grouped into groups. Therefore, it is important to note that the HAVING clause is applied after whereas the WHERE clause is applied before the GROUP BY clause.

Can I use HAVING Without GROUP BY clause?

Having can be used without groupby clause,in aggregate function,in that case it behaves like where clause. groupby can be used without having clause with the select statement. 3. The having clause can contain aggregate functions.

What is the purpose of the SQL AS clause?

The AS clause in SQL is used to change the column name in the output or assign a name to a derived column.

What is GROUP BY clause in SQL?

The GROUP BY clause is a SQL command that is used to group rows that have the same values. The GROUP BY clause is used in the SELECT statement. Optionally it is used in conjunction with aggregate functions to produce summary reports from the database.

WHERE is SQL?

WHERE clauses are not mandatory clauses of SQL DML statements, but can be used to limit the number of rows affected by a SQL DML statement or returned by a query. In brief SQL WHERE clause is used to extract only those results from a SQL statement, such as: SELECT , INSERT , UPDATE , or DELETE statement.

What are SQL views?

In SQL, a view is a virtual table based on the result-set of an SQL statement. A view contains rows and columns, just like a real table. The fields in a view are fields from one or more real tables in the database.

What is difference between ORDER BY and GROUP BY?

Group by statement is used to group the rows that have the same value. Whereas Order by statement sort the result-set either in ascending or in descending order. … In select statement, it is always used before the order by keyword. While in select statement, it is always used after the group by keyword.

What is foreign key in table?

A FOREIGN KEY is a field (or collection of fields) in one table, that refers to the PRIMARY KEY in another table. The table with the foreign key is called the child table, and the table with the primary key is called the referenced or parent table.