Quick Answer: How Does The Where Clause Work In SQL?

Which is not DDL command?


In SQL, which of the following is not a data definition language commands.

Explanation: With RENAME statement you can rename a table.

RENAME, REVOKE and GRANT are DDL commands and UPDATE is DML command..

Does order of where clause affect performance?

3 Answers. SQL was designed to be a declarative language, not a procedural one. So the query optimizer should not consider the order of the where clause predicates in determining how to apply them. … In a simple SQL query optimizer, the SQL statement first gets compiled into a tree of relational algebra operations.

How do I select duplicate rows in SQL?

To select duplicate values, you need to create groups of rows with the same values and then select the groups with counts greater than one. You can achieve that by using GROUP BY and a HAVING clause.

How do I select distinct rows in SQL?

To do this, you use the SELECT DISTINCT clause as follows: SELECT DISTINCT column_name FROM table_name; The query returns only distinct values in the specified column. In other words, it removes the duplicate values in the column from the result set.

What are the different functions in SQL?

SQL FunctionsAVG() – Returns the average value.COUNT() – Returns the number of rows.FIRST() – Returns the first value.LAST() – Returns the last value.MAX() – Returns the largest value.MIN() – Returns the smallest value.SUM() – Returns the sum.

How do I select a minimum value in SQL?

To find the minimum value of a column, use the MIN() aggregate function; it takes as its argument the name of the column for which you want to find the minimum value. If you have not specified any other columns in the SELECT clause, the minimum will be calculated for all records in the table.

Can you use count in a where clause SQL?

SQL COUNT( ) with where clause The WHERE clause can be used along with SQL COUNT() function to select specific records from a table against a given condition.

Can function be used in where clause?

SQL Server offers many handy functions that can be used either in your SELECT clause or in your WHERE clause. For the most part these functions provide complex coding that would be very difficult to get this same functionality without these functions.

How do I count rows in SQL query?

SQL COUNT(), AVG() and SUM() Functions The COUNT() function returns the number of rows that matches a specified criterion. The AVG() function returns the average value of a numeric column. The SUM() function returns the total sum of a numeric column.

Which of the following SQL commands is used to retrieve data?

SELECT query is used to retrieve data from a table. It is the most used SQL query.

How do you select a min in SQL?

The SQL MIN() and MAX() FunctionsSELECT MIN(column_name) FROM table_name. WHERE condition;SELECT MAX(column_name) FROM table_name. WHERE condition;Example. SELECT MIN(Price) AS SmallestPrice. FROM Products;Example. SELECT MAX(Price) AS LargestPrice. FROM Products;

Can we use MIN function in where clause?

Using MySQL MIN() with a WHERE clause example. This example uses the MIN() function to find the lowest buy price of all motorcycles: SELECT MIN(buyPrice) FROM products WHERE productline = ‘Motorcycles’; … Second, use the MIN() function to get the lowest value of the buy price of all motorcycles.

Which SQL keyword is used to retrieve a maximum value?

MAXMAX() is the SQL keyword is used to retrieve the maximum value in the selected column.

How do I count records in SQL?

SQL COUNT() FunctionSQL COUNT(column_name) Syntax. The COUNT(column_name) function returns the number of values (NULL values will not be counted) of the specified column: … SQL COUNT(*) Syntax. The COUNT(*) function returns the number of records in a table: … SQL COUNT(DISTINCT column_name) Syntax.

What is the purpose of SQL as clause?

SQL AS keyword is used to give an alias to table or column names in the queries. In this way, we can increase the readability and understandability of the query and column headings in the result set.

Where is SQL?

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

Can we use Max in where clause?

MAX() function with Having The SQL HAVING CLAUSE is reserved for aggregate function. The usage of WHERE clause along with SQL MAX() have also described in this page. The SQL IN OPERATOR which checks a value within a set of values and retrieve the rows from the table can also be used with MAX function.