sqlvar: Inserts SQL variables

  The 'sqlvar' tag safely inserts variables into SQL code. This tag is
  used in SQL Methods.

  Syntax

    'sqlvar' tag syntax::

      <dtml-sqlvar Variable|expr="VariableExpression">

    The 'sqlvar' tag is a singleton. Like the 'var' tag, the 'sqlvar'
    tag looks up a variable and inserts it. Unlike the var tag, the
    formatting options are tailored for SQL code.

  Attributes

    type=string -- The type of the variable. Valid types include:
    'string', 'int', 'float' and 'nb'. 'nb' means non-blank string and
    should be used in place of 'string' unless you want to use blank
    strings. The type attribute is required and is used to properly
    escape inserted variable.

    optional=boolean -- If true and the variable is null or
    non-existent, then nothing is inserted.

  Examples

    Basic usage::

      select * from employees 
        where name=<dtml-sqlvar name type="nb">

    This SQL quotes the 'name' string variable.

  See Also

    "sqltest tag":dtml-sqltest.stx