sqltest: Formats SQL condition tests

  The 'sqltest' tag inserts a condition test into SQL code. It tests a
  column against a variable. This tag is used in SQL Methods.

  Syntax

    'sqltest' tag syntax::

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

    The 'sqltest' tag is a singleton. It inserts a SQL condition test
    statement. It is used to build SQL queries. The 'sqltest' tag
    correctly escapes the inserted variable. The named variable or
    variable expression is tested against a SQL column using the
    specified comparison operation.

  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 instead of 'string' unless you want to test for
    blank values. The type attribute is required and is used to
    properly escape inserted variable.

    column=string -- The name of the SQL column to test against. This
    attribute defaults to the variable name.

    multiple=boolean -- If true, then the variable may be a sequence
    of values to test the column against.

    optional=boolean -- If true, then the test is optional and will
    not be rendered if the variable is empty or non-existent.

    op=string -- The comparison operation. Valid comparisons include: 

      eq -- equal to
      
      gt -- greater than

      lt -- less than

      ne -- not equal to

      ge -- greater than or equal to

      le -- less than or equal to

      The comparison defaults to equal to. If the comparison is not
      recognized it is used anyway. Thus you can use comparisons such
      as 'like'.

  Examples

    Basic usage::

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

    If the 'name' variable is 'Bob' then this renders::

      select * from employees
        where name = 'Bob'
     
    Multiple values::

      select * from employees
        where <dtml-sqltest empid type=int multiple>
    
    If the 'empid' variable is '(12,14,17)' then this renders::

      select * from employees
        where empid in (12, 14, 17)
 
  See Also

    "sqlgroup tag":dtml-sqlgroup.stx

    "sqlvar tag":dtml-sqlvar.stx