SQL Table
Table is a collection of data, organized in terms of rows and columns. In DBMS term, table is known as relation and row as tuple.
Note: A table has a specified number of columns, but can have any number of rows.
Table is the simple form of data storage. A table is also considered as a convenient representation of relations.
Let's see an example of an employee table:
| EMP_NAME | ADDRESS | SALARY |
|---|---|---|
| Ankit | Lucknow | 15000 |
| Raman | Allahabad | 18000 |
| Mike | New York | 20000 |
In the above table, "Employee" is the table name, "EMP_NAME", "ADDRESS" and "SALARY" are the column names. The combination of data of multiple columns forms a row e.g. "Ankit", "Lucknow" and 15000 are the data of one row.
SQL TABLE Variable
The SQL Table variable is used to create, modify, rename, copy and delete tables. Table variable was introduced by Microsoft.
It was introduced with SQL server 2000 to be an alternative of temporary tables.
It is a variable where we temporary store records and results. This is same like temp table but in the case of temp table we need to explicitly drop it.
Table variables are used to store a set of records. So declaration syntax generally looks like CREATE TABLE syntax.
("column1" "data type",
"column2" "data type",
...
"columnN" "data type");
When a transaction rolled back the data associated with table variable is not rolled back.
A table variable generally uses lesser resources than a temporary variable.
Table variable cannot be used as an input or an output parameter.
Topics of SQL TABLE Statement
SQL TABLE Variable
What TABLE variable can do?
SQL CREATE TABLE
How to create a table using SQL query>
SQL DROP TABLE
How to drop a table?
SQL DELETE TABLE
How to delete all the records of a table?
SQL RENAME TABLE
How to rename a table?
SQL TRUNCATE TABLE
How to truncate a table?
SQL COPY TABLE
How to copy a table?
SQL TEMP TABLE
What is temporary table? What are the advantage of temporary table?
SQL ALTER TABLE
How to add, modify, rename and drop column.
