SQL Introduction (standard, differences on different databases)

SQL is the standard computer language for accessing and working with databases

Using SQL, you can access and manipulate data in a data system such as: Oracle,sybase,sql server,db2,access, etc.

　　

What can SQL do?

• SQL database-oriented query execution
• SQL can retrieve data from the database
• SQL can insert new records in the database
• SQL can update data in a database
• SQL to delete records from the database
• SQL to create a new database
• SQL to create a new table in the database
• SQL can create stored procedures in the database
• SQL to create views in the database
• SQL can set permissions for tables, stored procedures, and views

SQL is a standard, but ...

SQL is an ANSI standard computer language used to access and manipulate database systems. SQL statements are used to retrieve and update data in the database. SQL can work with database programs, such as Ms Access, DB2, Informix, MS SQL Server, Oracle, Sybase, and other database systems

Unfortunately, there are many different versions of the SQL language, but to be compatible with ANSI standards, they must collectively support some key keywords (such as SELECT, UPDATE, DELETE, INSERT, where, and so on) in a similar way

But in addition to the SQL standard, most SQL database programs have their own private extensions

Rdbms

RDBMS refers to a relational database management system.

The RDBMS is the foundation of SQL and is also the foundation of all modern database systems, such as MS SQL Server, IBM DB2, Oracle, MySQL, and Microsoft Access.

Data in an RDBMS is stored in a database object called a table (tables).

A table is a collection of related data items that consists of columns and rows.

SQL Introduction (standard, differences on different databases)