Name

SELECT —

Function

Syntax

       (SELECT &REST SELECT-ALL-ARGS) [function] => 

Arguments and Values

Description

Executes a query on DATABASE, which has a default value of *DEFAULT-DATABASE*, specified by the SQL expressions supplied using the remaining arguments in SELECT-ALL-ARGS. The SELECT argument can be used to generate queries in both functional and object oriented contexts. In the functional case, the required arguments specify the columns selected by the query and may be symbolic SQL expressions or strings representing attribute identifiers. Type modified identifiers indicate that the values selected from the specified column are converted to the specified lisp type. The keyword arguments ALL, DISTINCT, FROM, GROUP-by, HAVING, ORDER-BY, SET-OPERATION and WHERE are used to specify, using the symbolic SQL syntax, the corresponding components of the SQL query generated by the call to SELECT. RESULT-TYPES is a list of symbols which specifies the lisp type for each field returned by the query. If RESULT-TYPES is nil all results are returned as strings whereas the default value of :auto means that the lisp types are automatically computed for each field. FIELD-NAMES is t by default which means that the second value returned is a list of strings representing the columns selected by the query. If FIELD-NAMES is nil, the list of column names is not returned as a second value. In the object oriented case, the required arguments to SELECT are symbols denoting View Classes which specify the database tables to query. In this case, SELECT returns a list of View Class instances whose slots are set from the attribute values of the records in the specified table. Slot-value is a legal operator which can be employed as part of the symbolic SQL syntax used in the WHERE keyword argument to SELECT. REFRESH is nil by default which means that the View Class instances returned are retrieved from a cache if an equivalent call to SELECT has previously been issued. If REFRESH is true, the View Class instances returned are updated as necessary from the database and the generic function INSTANCE-REFRESHED is called to perform any necessary operations on the updated instances. In both object oriented and functional contexts, FLATP has a default value of nil which means that the results are returned as a list of lists. If FLATP is t and only one result is returned for each record selected in the query, the results are returned as elements of a list.

Examples

        
      

Side Effects

Affected by

Exceptional Situations

See Also

Notes