What is SQL ?

What is SQL ?

SQL

·        SQL stands for Structured Query Language, which is used to communicate with the database.

·        It requires an environment to implement its features in the form of statements.

·        Database server know only Sequel language.

·        SQL lets you access and manipulate databases

  • It is non-procedural language.
  • Case incentive language.
  • The Commands cannot be abbreviated.
  • It’s statements can spread on to multiple lines(any number of lines).
  • It support ANSI(American National Standards Institute) standard.

Why it’s is non-procedural language ?

We know that in sequel ,always write statements, we don’t write any program or don’t write any procedural steps or step-by-step process ,so sequel is is non-procedural language.

Example

select sal from emp where empno=7499;
----------------------------------------
1600

  1. Suppose emp-table is not present in the database, then output will be table doesn’t exit.
  2. If column is not in the table, then output will be invalid identifier.
  3. Table is present, column is also present in database, but there is no data is in table. then output will be No rows selected.

From one statements , We get various types output, so SQL is non-procedural language.

What Can SQL do?

  • Can execute queries against a database
  • It can retrieve data from a database
  • Can insert records in a database
  • Update records in a database
  • Delete records from a database
  • Create new databases
  • Can create new tables in a database
  • It can create stored procedures in a database
  • Can create views in a database
  • It can set permissions on tables, procedures, and views

SQL COMAND

SQL COMANDS
SQL COMANDS

what is oracle architecture ?

RDBMS

RDBMS stands for Relational Database Management System.

RDBMS is the basis for SQL, and for all modern database systems such as MS SQL Server, IBM DB2, Oracle, MySQL, and Microsoft Access.

The data in RDBMS is stored in database objects called tables. A table is a collection of related data entries and it consists of columns and rows.

Look at the “Customers” table:

 

select * from emp;

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