Variables

vsql provides variable substitution features similar to common Linux command shells. Variables are simply name/value pairs, where the value can be any string of any length. To set variables, use the vsql meta-command \set:

Sets the internal variable name to value or, if more than one value is given, to the concatenation of all of them. If no second argument is given, the variable is set with no value. To unset a variable, use the \ unset command.

Valid variable names can contain characters, digits, and underscores. See the section Variables below for details. Variable names are case-sensitive.

Note: vsql treats several variables as special. They are documented in Variables.

sets the variable foo to the value bar. To retrieve the content of the variable, precede the name with a colon and use it as the argument of any slash command:

Note: The arguments of \set are subject to the same substitution rules as with other commands. For example, \set bar :foo is a valid way to copy a variable.

If you call \set without a second argument, the variable is set, with an empty string as value. To unset (or delete) a variable, use the command \unset.

vsql's internal variable names can consist of letters, numbers, and underscores in any order and any number. Some of these variables are treated specially by vsql. They indicate certain option settings that can be changed at run time by altering the value of the variable or represent some state of the application. Although you can use these variables for any other purpose, this is not recommended. By convention, all specially treated variables consist of all upper-case letters (and possibly numbers and underscores). To ensure maximum compatibility in the future, avoid using such variable names for your own purposes.

An additional useful feature of vsql variables is that you can substitute ("interpolate") them into regular SQL statements. The syntax for this is again to prepend the variable name with a colon (:).

would then query the table my_table. The value of the variable is copied literally, so it can even contain unbalanced quotes or backslash commands. Make sure that it makes sense where you put it. Variable interpolation is not performed into quoted SQL entities.