SQL-EXPRESSION — Constructs an SQL expression from supplied keyword arguments.
Function
stringA string.
tableA symbol representing a database table identifier.
aliasA table alias.
attributeA symbol representing an attribute identifier.
typeA type specifier.
A object of type sql-expression.
Returns an SQL expression constructed from the supplied arguments which may be combined as follows:
            attribute and
            type; 
          
 
            attribute; 
          
 
            alias or table and
            attribute and
            type; 
          
 
            alias or
            table and
            attribute; 
          
 
            table,
            attribute and
            type; 
          
 
            table and
            attribute; 
          
 
            table
            and alias; 
          
 
            table; 
          
            string.
          
(sql-expression :table 'foo :attribute 'bar)
=> #<CLSQL-SYS:SQL-IDENT-ATTRIBUTE FOO.BAR>
(sql-expression :attribute 'baz)
=> #<CLSQL-SYS:SQL-IDENT-ATTRIBUTE BAZ>
      An error of type sql-user-error
      is signalled if an unsupported combination of keyword arguments is 
      specified.