A standard language for dealing with RDBMS. So, data can be visualized as being stored in tables.
Help and tutorials
w3schools has a good tutorial.
Values
Strings are enclosed as here: ‘asdf’.
Query language
Query table
The query table may be specified in several ways. In the most basic case, it is a single table.
- table1 (as t1), table2 represents a cross-product, aka cross join. This returns a table whose rows are members of tbl1 X tbl2. In specifying temporary table names, as in table1 as t1, some dialects allow omission of ‘as’.
- tableList may be of the form: tbl1 join-command tbl2 [on condition]
- Or it can be: (selectStatement)
Post selection processing
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‘group by fieldName’ groups the data together before displaying.
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Multiple select statements may be combined using keywords like: UNION ALL, INTERSECT.
Temporary tables
Temporary or inline tables are automatically created whenever a query table involves a join of any sort, or when it is defined by some select statement.
However, one may want to explicitly name and store the results of a query. Syntax is same as in create statement, with additional keyword: create temporary/ inline table.
Storage
These tables are stored in the RAM of the database client or on the database server.
The tables are dropped automatically at the end of the session.
Stored procedures
A piece of sql code which can be easily called.