Using SQLite

Column Names

One of the most common types of expressions is the column name. The general format is fairly simple, consisting of just the column name. If there is any ambiguity between different tables, you can prefix the column name with an optional table name or a database and table name.

Identifiers (database names, table names, or column names) that include nonstandard characters can be enclosed in double quotes ( "" ) or square brackets ( [] ) to escape them. For example [table name].[column name].

Column name expressions are always evaluated in some type of context. For example, if you’re formulating a WHERE expression that is part of a SELECT statement, the expression defined there will be evaluated once for each possible row in the result set. As each row is processed, the value of the column for that row will be put into the expression and the expression will be evaluated. The context defines what column references are available to any particular expression.

In addition to actual table columns, many expressions within a SELECT statement can also reference columns from the result set by referencing the alias assigned in an AS clause. Similarly, if a source table in the FROM clause is assigned a table alias, this alias must be used in any table reference. The use of table aliases is especially common when formulating join condition expressions on self-joins (a table joined to itself), ...