Introduction To SQL
Arithmetic Functions in SQL
Many of the uses we have for the data we retrieve involve mathematics. Most implementations of SQL provide arithmetic functions similar to the functions covered here.
Character Functions in SQL
Many implementations of SQL provide functions to manipulate characters and strings of characters. This section covers the most common character functions.
Conversion Functions in SQL
Functions in SQL enable we to perform feats such as determining the sum of a column or converting all the characters of a string to uppercase.
General Functions in SQL
Functions in SQL enable we to perform feats such as determining the sum of a column or converting all the characters of a string to uppercase.
Joins in SQL
One of the most powerful features of SQL is its capability to gather and manipulate data from across several tables. Without this feature we would have to store all the data elements necessary for each application in one table. Without common tables we would need to store the same data in several tables. Imagine having to redesign, rebuild, and repopulate our tables and databases every time our user needed a query with a new piece of information. The JOIN statement of SQL enables us to design smaller, more specific tables that are easier to maintain than larger tables.