Re: executing dynamic commands - Mailing list pgsql-sql

Thanx for the quick response !
Sorry for asking a bit confusing question ... Using the View is a good idea but does not fully solve my problem. To
makeit a bit more clear: I want to copy all records from table1 to table2 assuming that the two tables have exactly the
samecolumn definition and column order. I could do that executing INSERT INTO tablefoo1 SELECT * FROM tablefoo2;
 
But how can I do the copying if the column order is different between tablefoo1 and tablefoo2 ?
My approach was to dynamically assemble a string1 with all fieldnames and a string2 with the corresponding field values
rowper row using a plpgsql function. The result would be a row per row copying using INSERT INTO tablefoo1 (string1)
VALUES(string2). My problem is that I not manage to read the fieldvalues row by row. 
 
Do you have any idea ?

Thanx a lot !

Regards

Chris


>
>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 AS
> SELECT 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
>            ELSE true
>        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
>            ELSE NULL::character varying
>        END AS label
>   FROM ONLY pg_class pc
>   JOIN ONLY pg_attribute pa ON pc.oid = pa.attrelid AND 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.objoid AND 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
>> 
>
>
>
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