Quick Answer: How Can I See All Tables In SQL?

Is view better than table?

7 Answers.

A table contains data, a view is just a SELECT statement which has been saved in the database (more or less, depending on your database).

The advantage of a view is that it can join data from several tables thus creating a new view of it..

Which is better view or stored procedure?

A view is essentially a saved SQL statement. Therefore, I would say that in general, a stored procedure will be likely to be faster than a view IF the SQL statement for each is the same, and IF the SQL statement can benefit from optimizations. Otherwise, in general, they would be similar in performance.

How do I view tables in SQL?

The easiest way to see all tables in the database is to query the all_tables view: SELECT owner, table_name FROM all_tables; This will show the owner (the user) and the name of the table. You don’t need any special privileges to see this view, but it only shows tables that are accessible to you.

Can you join 3 tables in SQL?

Joining three tables in single SQL query can be very tricky if you are not good with the concept of SQL Join. … Between all of these fundamentals, What is most important about Join is, combining multiple tables. If you need data from multiple tables in one SELECT query you need to use either subquery or JOIN.

How do I drop all tables in a database?

How to drop all tables in MySQL?SET FOREIGN_KEY_CHECKS = 0; … SELECT table_name FROM information_schema.tables WHERE table_schema = db_name; … DROP TABLE IF EXISTS table1; DROP TABLE IF EXISTS table2; DROP TABLE IF EXISTS table3; … SET FOREIGN_KEY_CHECKS = 1; … echo “SET FOREIGN_KEY_CHECKS = 0;” > ./temp.sql.More items…•

Can you join two views SQL?

In combining views, we can’t simply use JOINs (which JOIN columns). Instead we use UNION. UNION must have same number of columns and compatible types before and after the UNION.

How do you join views?

A join view executes the relational algebra operation JOIN on a series of input views. These views can belong to different databases. To create a join view, click Join on the File > New menu or, right-click the Server Explorer and click Join on the menu New.

Which is faster view or table?

MS SQL Indexed views are faster than a normal view or query but indexed views can not be used in a mirrored database invironment (MS SQL). … In this situation a temporary table using # or @ to hold your data to loop through is faster than a view or a query. So it all depends on the situation.

How do I drop all tables from database with one SQL query?

In SSMS:Right click the database.Go to “Tasks”Click “Generate Scripts”In the “Choose Objects” section, select “Script entire database and all database objects”In the “Set Scripting Options” section, click the “Advanced” button.On “Script DROP and CREATE” switch “Script CREATE” to “Script DROP” and press OK.More items…

Can we join two views in Oracle?

A join is a query that combines rows from two or more tables, views, or materialized views. Oracle Database performs a join whenever multiple tables appear in the FROM clause of the query. The select list of the query can select any columns from any of these tables.

How do I view multiple tables in SQL?

To create a view, a user must have the appropriate system privilege according to the specific implementation. CREATE VIEW view_name AS SELECT column1, column2….. FROM table_name WHERE [condition]; You can include multiple tables in your SELECT statement in a similar way as you use them in a normal SQL SELECT query.

How do I see all tables in SQL Developer?

To view tables:In the Connections navigator in SQL Developer, navigate to the Tables node for the schema that includes the table you want to display. If the view is in your own schema, navigate to the Tables node in your schema. … Open the Tables node. … Click the name of the table that you want to display.

Why drop table if exists?

The DROP TABLE SQL statement enables you to delete a table from the database. If the table did not exist then attempting to DROP it would cause an error to occur. The DROP TABLE IF EXISTS SQL statement enables a check to see that the table exists prior to attempting the dropping (deletion) of the table.

How do I drop all tables in SQL Plus?

select ‘drop table ‘||table_name||’ cascade constraints;’ from user_tables; This will print out a series of drop commands for all tables in the schema. Spool the result of this query and execute it. BEGIN FOR c IN (SELECT table_name FROM user_tables) LOOP EXECUTE IMMEDIATE (‘DROP TABLE “‘ || c.

How do you do a join in SQL?

SQL INNER JOIN KeywordSELECT column_name(s) FROM table1. INNER JOIN table2. ON table1.column_name = table2.column_name;Example. SELECT Orders.OrderID, Customers.CustomerName. FROM Orders. INNER JOIN Customers ON Orders.CustomerID = Customers.CustomerID;Example. SELECT Orders.OrderID, Customers.CustomerName, Shippers.ShipperName. FROM ((Orders.

How many types of joins in SQL?

five typesANSI-standard SQL specifies five types of JOIN : INNER , LEFT OUTER , RIGHT OUTER , FULL OUTER and CROSS . As a special case, a table (base table, view, or joined table) can JOIN to itself in a self-Join. A programmer declares a JOIN statement to identify rows for joining.

What is difference between view and table?

A view is a virtual table. A view consists of rows and columns just like a table. The difference between a view and a table is that views are definitions built on top of other tables (or views), and do not hold data themselves. If data is changing in the underlying table, the same change is reflected in the view.

Can we join view and table SQL?

2 Answers. Joins against views work exactly like joins against tables. Just use the view name in place of a regular table name.

How can I retrieve data from two tables in SQL?

In SQL, to fetch data from multiple tables, the join operator is used. The join operator adds or removes rows in the virtual table that is used by SQL server to process data before the other steps of the query consume the data.