What Are The Clauses In SQL Server?

What are the clauses in SQL?

SQL clausesCONSTRAINT clause.

A CONSTRAINT clause is an optional part of a CREATE TABLE statement or an ALTER TABLE statement.

EXTERNAL NAME clause.

FOR UPDATE clause.

FROM clause.

GROUP BY clause.

HAVING clause.

WINDOW clause.

ORDER BY clause.More items….

What does count (*) do in SQL?

COUNT(*) returns the number of rows in a specified table, and it preserves duplicate rows. It counts each row separately. This includes rows that contain null values. The partition_by_clause divides the result set produced by the FROM clause into partitions to which the COUNT function is applied.

What is the difference between where and having in SQL?

The main difference between WHERE and HAVING clause comes when used together with GROUP BY clause, In that case WHERE is used to filter rows before grouping and HAVING is used to exclude records after grouping. This is the most important difference and if you remember this, it will help you write better SQL queries.

How do I count distinct rows in SQL?

We can use SQL Count Function to return the number of rows in the specified condition. The syntax of the SQL COUNT function: COUNT ([ALL | DISTINCT] expression); By default, SQL Server Count Function uses All keyword.

Which is faster where or having?

Both the statements will be having same performance as SQL Server is smart enough to parse both the same statements into a similar plan. So, it does not matter if you use WHERE or HAVING in your query. … “WHERE” is faster than “HAVING”!

What is the difference between where and having clauses?

WHERE Clause is used to filter the records from the table based on the specified condition. … HAVING Clause is used to filter record from the groups based on the specified condition.

Can we use where and having together in SQL?

A query can contain both a WHERE clause and a HAVING clause. … The HAVING clause is then applied to the rows in the result set. Only the groups that meet the HAVING conditions appear in the query output. You can apply a HAVING clause only to columns that also appear in the GROUP BY clause or in an aggregate function.

How do I select specific rows in SQL?

To select rows using selection symbols for character or graphic data, use the LIKE keyword in a WHERE clause, and the underscore and percent sign as selection symbols. You can create multiple row conditions, and use the AND, OR, or IN keywords to connect the conditions.

Which SQL keyword is used to retrieve a maximum value?

Which SQL keyword is used to retrieve a maximum value? Explanation: The MAX() function returns the largest value of the selected column.

What is the difference between count and count (*)?

COUNT(*) counts the rows in your table. COUNT(column) counts the entries in a column – ignoring null values. Of course there will be performance differences between these two, but that is to be expected if they are doing different things.

What is top clause in SQL?

The SQL SELECT TOP Clause The SELECT TOP clause is used to specify the number of records to return. The SELECT TOP clause is useful on large tables with thousands of records. … MySQL supports the LIMIT clause to select a limited number of records, while Oracle uses ROWNUM.

How do I select top 5 rows in SQL?

SQL SELECT TOP ClauseSQL Server / MS Access Syntax. SELECT TOP number|percent column_name(s) FROM table_name;MySQL Syntax. SELECT column_name(s) FROM table_name. LIMIT number;Example. SELECT * FROM Persons. LIMIT 5;Oracle Syntax. SELECT column_name(s) FROM table_name. WHERE ROWNUM <= number;Example. SELECT * FROM Persons.

How do I get the first 10 rows in SQL?

The ANSI SQL answer is FETCH FIRST . If you want ties to be included, do FETCH FIRST 10 ROWS WITH TIES instead. To skip a specified number of rows, use OFFSET , e.g. Will skip the first 20 rows, and then fetch 10 rows.

How do I get last 3 records in SQL?

SELECT * FROM (select * from suppliers ORDER BY supplier_name DESC) suppliers2 WHERE rownum <= 3 ORDER BY rownum DESC; Notice that although you want the last 3 records sorted by supplier_name in ascending order, you actually sort the supplier_name in descending order in this solution.

How do I select the top 3 rows in SQL?

SQL Server SELECT TOPexpression. Following the TOP keyword is an expression that specifies the number of rows to be returned. … PERCENT. … WITH TIES. … 1) Using TOP with a constant value. … 2) Using TOP to return a percentage of rows. … 3) Using TOP WITH TIES to include rows that match the values in the last row.

What is the difference between count 1 and count (*) in a SQL query?

The difference is simple: COUNT(*) counts the number of rows produced by the query, whereas COUNT(1) counts the number of 1 values. Note that when you include a literal such as a number or a string in a query, this literal is “appended” or attached to every row that is produced by the FROM clause.

Which of the following is an illegal data type in SQL?

A directory of Objective Type Questions covering all the Computer Science subjects. Here you can access and discuss Multiple choice questions and answers for various compitative exams and interviews….Discussion Forum.Que.Which of the following is an illegal data type in SQLc.blobd.lintAnswer:lint2 more rows

How can we insert data into a view?

‘100000.00’; To explain the INSERT INTO statement, I’m simply using SELECT after the name of our view, which is a very simple way to insert data into tables as we’re inserting new data based on the result of the SELECT statement. As can be seen, we can do data modifications through views.

Can you have two where clauses in SQL?

You can specify multiple conditions in a single WHERE clause to, say, retrieve rows based on the values in multiple columns. You can use the AND and OR operators to combine two or more conditions into a compound condition. AND, OR, and a third operator, NOT, are logical operators.

Is Rownum stored in database?

Both, rownum and rowed are pseudo columns. For each row in the database, the ROWID pseudocolumn returns the address of the row. For each row returned by a query, the ROWNUM pseudocolumn returns a number indicating the order in which Oracle selects the row from a table or set of joined rows.

How do I get last 10 rows in SQL?

The following is the syntax to get the last 10 records from the table. Here, we have used LIMIT clause. SELECT * FROM ( SELECT * FROM yourTableName ORDER BY id DESC LIMIT 10 )Var1 ORDER BY id ASC; Let us now implement the above query.

How do I get last 5 rows in SQL?

You need to count number of rows inside table ( say we have 12 rows )then subtract 5 rows from them ( we are now in 7 )select * where index_column > 7 select * from users where user_id > ( (select COUNT(*) from users) – 5) you can order them ASC or DESC.

How do I select the number of rows in SQL?

If you’d like to number each row in a result set, SQL provides the ROW_NUMBER() function. This function is used in a SELECT clause with other columns. After the ROW_NUMBER() clause, we call the OVER() function. If you pass in any arguments to OVER , the numbering of rows will not be sorted according to any column.