YouTip

# SQL Guide * * * ## SQL - Structured Query Language (Structured Query Language) SQL is the standard computer language for accessing and processing databases. Common database management systems: MySQL, SQL Server, Access, Oracle, Sybase, and DB2 For those who want to store data in a database and retrieve data from it, knowledge of SQL is invaluable. * * * ## What is SQL? * SQL stands for Structured Query Language (_S_ tructured _Q_ uery _L_ anguage) * SQL allows us to access databases * SQL is a standard computer language by ANSI * SQL is used to query databases * SQL can retrieve data from databases * SQL can insert new records into databases * SQL can delete records from databases * SQL is easy to learn * * * ## SQL Database Tables A database usually contains one or more tables. Each table is identified by a name (e.g., "Customers" or "Orders"). A table contains records (rows) with data. The following example is a table named "Persons": | LastName | FirstName | Address | City | | :--- | :--- | :--- | :--- | | Hansen | Ola | Timoteivn 10 | Sandnes | | Svendson | Tove | Borgvn 23 | Sandnes | | Pettersen | Kari | Storgt 20 | Stavanger | The above table contains three records (each corresponding to a person) and four columns (last name, first name, address, and city). * * * ## SQL Query Programs With SQL, we can query a database and get a result set back. A query program looks like this: SELECT LastName FROM Persons The result set looks like this: | LastName | | :--- | | Hansen | | Svendson | | Pettersen | * * * ## How to Learn SQL? Visit our (#)