What does drop table if exists do in SQL?

The DROP TABLE statement deletes the specified table, and any data associated with it, from the database. The IF EXISTS clause allows the statement to succeed even if the specified tables does not exist. If the table does not exist and you do not include the IF EXISTS clause, the statement will return an error.

What happens if you DROP a table on which a view exists?

Dropping a table removes the table definition from the data dictionary. All rows of the table are no longer accessible. All indexes and triggers associated with a table are dropped. All views and PL/SQL program units dependent on a dropped table remain, yet become invalid (not usable).

What does dropping a table do?

The drop table command is used to delete a table and all rows in the table. To delete an entire table including all of its rows, issue the drop table command followed by the tablename. … Dropping the table removes the table definition as well as all of its rows.

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How do I know if a table exists before dropping?

Another way to see if a table exists is by querying the sys. tables system view to see if there is an entry for the table and schema names. DROP TABLE will not run because there is no row returned from sys. systables in the EXISTS clause.

How do you check if a table exists in SQL?

To check if a table exists in SQL Server, you can use the INFORMATION_SCHEMA. TABLES table. You can use this table with an IF THEN clause do determine how your query responds whether or not a table exists. One of the more common uses I find for this when I need to create a table in a script.

Does the SQL view exists if the table is dropped from the database?

Answer: Yes, in Oracle, the SQL VIEW continues to exist even after one of the tables (that the SQL VIEW is based on) is dropped from the database. However, if you try to query the SQL VIEW after the table has been dropped, you will receive a message indicating that the SQL VIEW has errors.

What happens to the data associated with a view when the view is dropped?

Anytime you DROP anything using the SQL DROP command, you should feel a little nervous tension. After all, something is being removed (possibly permanently) from the database! However, with by dropping a view, the original data is unaffected.

Do we need to commit after DROP TABLE?

Data definition language (DDL) statements that define or modify database objects. … CREATE TABLE and DROP TABLE statements do not commit a transaction if the TEMPORARY keyword is used. (This does not apply to other operations on temporary tables such as ALTER TABLE and CREATE INDEX , which do cause a commit.)

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Does DROP TABLE free up space?

Dropping a table will free up the space within the database, but will not release the space back to Windows. That requires shrinking the database file.

How DROP and recreate table in SQL Server?

If You are using SQL Server Management Studio, You could generate a DROP and RECREATE script with “Keep schema and data” option.

  1. Right click on the desired DB in object explorer.
  2. Tasks > Generate scripts.
  3. Select the table you want to script.
  4. Then clicking on Advanced button.

How do you create table if not exists in SQL?

In this syntax:

  1. First, specify the name of the table that you want to create after the CREATE TABLE keywords. …
  2. Second, use IF NOT EXISTS option to create a new table if it does not exist. …
  3. Third, optionally specify the schema_name to which the new table belongs. …
  4. Fourth, specify the column list of the table.

How do I check if a database exists?

In creating a database you also need to check whether or not the database already exists. In order to do so, simply use the ‘if exists’ method and select the name of the database from sysdatabases. The code below will drop an existing database if it exists so be careful.

How do I know if a temp table exists?

Check If Temporary Table or Temp Table Exists in SQL Server…

  1. create table TestTable(id int) …
  2. create table #TestTable(id int) …
  3. select * from tempdb.sys.tables where name like ‘#TestTable%’
  4. select object_id(‘tempdb..#TestTable’,’U’)
  5. if object_id(‘tempdb..#TestTable’,’U’) is not null.

What is if not exists in SQL?

The SQL NOT EXISTS Operator will act quite opposite to EXISTS Operator. It is used to restrict the number of rows returned by the SELECT Statement. The NOT EXISTS in SQL Server will check the Subquery for rows existence, and if there are no rows then it will return TRUE, otherwise FALSE.

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What SQL statement we use to bring all the values of particular table?

The SELECT statement is used to select or retrieve the data from one or more tables. You can use this statement to retrieve all the rows from a table in one go, as well as to retrieve only those rows that satisfy a certain condition or a combination of conditions.

How write if exists in SQL Server?

The following code does the below things for us:

  1. First, it executes the select statement inside the IF Exists.
  2. If the select statement returns a value that condition is TRUE for IF Exists.
  3. It starts the code inside a begin statement and prints the message.