Re: executing dynamic commands - Mailing list pgsql-sql

Talk about obfuscated.... Are you trying to retrieve the table structure / 
schema from the PG System Catalogs ?

If so -- you are better off using a VIEW instead of a manual procedure 
because it will automatically kepp up with the current schema definition...

Try this:

-- DROP VIEW sys_table_schemas;

CREATE OR REPLACE VIEW sys_table_schemas ASSELECT pc.oid AS tbl_oid, pc.relname::character varying AS table_name, 
pa.attname::character varying AS column_name, pt.typname AS data_type,       CASE           WHEN
substr(pt.typname::text,1, 3)::name = 'int'::name THEN 
 
'integer'::name           WHEN pt.typname = 'bool'::name THEN 'boolean'::name           ELSE pt.typname       END AS
udt_name,pa.attnum AS ordinal_position, 254 AS str_length,       CASE           WHEN pa.attnotnull THEN false
ELSEtrue       END AS nulls_allowed,       CASE           WHEN substr(pa.attname::text, 1, 3) = 'lu_'::text THEN true
       ELSE false       END AS lookup,       CASE           WHEN pd.description::character varying IS NOT NULL THEN 
 
pd.description::character varying           WHEN pa.attname IS NOT NULL THEN pa.attname::character varying
ELSENULL::character varying       END AS label  FROM ONLY pg_class pc  JOIN ONLY pg_attribute pa ON pc.oid =
pa.attrelidAND pc.relnamespace = 
 
2200::oid AND pc.reltype > 0::oid AND (pc.relkind = 'r'::"char" OR 
pc.relkind = 'v'::"char")  JOIN ONLY pg_type pt ON pa.atttypid = pt.oid  LEFT JOIN ONLY pg_description pd ON pc.oid =
pd.objoidAND pa.attnum = 
 
pd.objsubid WHERE pa.attnum > 0 ORDER BY pc.relname::character varying, pa.attnum;

ALTER TABLE sys_table_schemas OWNER TO "public";

SELECT * FROM sys_table_schemas;




<christian.michels@eifelgeist.com> wrote in message 
news:15802822.125111138807576371.JavaMail.servlet@kundenserver...
> Hi,
>
> I user PostgreSQl 8.0.4 on Win2003 Server and write a function to copy 
> rows from one table into another table with the same column definition.
> My first approach was to use something like:
>
> query_value :=  'INSERT INTO ' || tabledest || ' SELECT * FROM ' || 
> tablesrc;
> EXECUTE query_value;
>
> This only works if the column definition AND the order between source and 
> destination is the same !
> In my case I have always the same column definitions but they are not in 
> the same order between source and destination table.
> What I tryed then is to loop through the column definition of the source 
> and query the sourcetable for the value. For that I have to execut a query 
> with dynamic tablename and dynamic columname to generate two stings one 
> with the columndefinitin and one with the columnvalues to exececute 
> something like: INSERT INTO tabelfoo (columndefinitinstring) VALUES 
> (columnvaluesstring)
>
> see snip of function:
>
> fieldvalues RECORD;
> output  RECORD;
> insertvalues VARCHAR;
> fieldname VARCHAR;
>
>
> -- Get Attribute List from Table and write it to output
> -- Read Values of Fieldname from source
> query_value :=  'select * from ' || tablesrc ;
>
> FOR fieldvalues IN EXECUTE query_value LOOP
>
>  FOR output IN SELECT a.attnum,
>    a.attname AS field,
>    FROM
>      pg_class c,  pg_attribute a,  pg_type t
>    WHERE
>      c.relname = tablesrc  AND
>      a.attnum > 0  AND
>      a.attrelid = c.oid  AND
>      a.atttypid = t.oid
>    ORDER BY a.attnum LOOP
>
>     -- Read Field Name from Out Table
>     fieldname := output.field;
>
>     -- Write Field Name into Variable
>     IF insertcolumns IS NULL THEN
>       insertcolumns := fieldname;
>     ELSE
>       insertcolumns := insertcolumns || ',' || fieldname;
>     END IF;
>
> Until here everyting is fine ... but now I try to query  the value from 
> RECORD fieldvalues with the columname fieldname variable from the inner 
> loop !
> I tryed the following ...
>
> query_value :=  'select quote_ident(' || fieldvalues || ').quote_literal(' 
> || fieldname ||')';
>
> EXECUTE query_value;
>
>
> and I get the following error message ...
>
> ERROR:  could not find array type for data type record
> CONTEXT:  SQL statement "SELECT  'select quote_ident(' ||  $1  || 
> ').quote_literal(' ||  $2  ||')'"
> PL/pgSQL function "prx_db__appendtable" line 87 at assignment
>
>
>      END LOOP;
>
>    END LOOP;
>
> I know the function is not runnable, but my question is  how can I 
> dynamically combine "fieldvalues"."fieldname" to read the values column by 
> colum out if a RECORD variable to generate the "columnvaluesstring" 
> mentioned above ?!
> Maybe this approach is to complicated and there is a quick and easy 
> solution ?!
>
> Any help is very much appreciated !!
>
> Thanx a lot & Regards
>
> Chris
>
> ---------------------------(end of broadcast)---------------------------
> TIP 9: In versions below 8.0, the planner will ignore your desire to
>       choose an index scan if your joining column's datatypes do not
>       match
>