I have table which has basically 2 rows containing the name of failure and the main table i want to write a query such that
Select main
from xyz
will return the table name like abc.
Now I want to get the data from the abc table
Select *
from
(select main
from xyz)
which returns abc.
How can I write it ?
You must use dynamic sql.
Note, that you can't use "SELECT to nowhere" in a compound statement in Db2. That is, the following code is erroneous.
BEGIN
SELECT * FROM MYTAB;
END#
This is why you need to store the result of SELECT somewhere. You may use Global Temporary Tables for that presuming, that USER TEMPORARY TABLESPASE is available to use for your user.
--#SET TERMINATOR #
BEGIN
DECLARE V_STMT VARCHAR (500);
SELECT
'DECLARE GLOBAL TEMPORARY TABLE SESSION.RESULT'
|| ' AS (SELECT * FROM '
|| MAIN
|| ') WITH DATA WITH REPLACE '
|| 'ON COMMIT PRESERVE ROWS NOT LOOGED'
INTO V_STMT
FROM XYZ
-- place your WHERE clause here if needed
FETCH FIRST 1 ROW ONLY
;
EXECUTE IMMEDIATE V_STMT;
END
#
SELECT * FROM SESSION.RESULT
#
dbfiddle link.
Here is a solution on stack that shows how to get the table names from your database
DB2 Query to retrieve all table names for a given schema
Then you could take your failure table and join into it based off of the table name, that should match your errors to the table that match on the table name. I'm not a 100% sure of your question but I think this is what you are asking.
The inner system query has schema and name. Type is T for table. See IBM link below for column reference. You could run the query wide open in the inner query to look for the tables you want. I would recommend using schema to isolate your search.
https://www.ibm.com/docs/en/db2-for-zos/11?topic=tables-systables
SELECT
ft.*
, st.*
FROM [FailureTable] as ft
INNER JOIN
(
select * from sysibm.systables
where CREATOR = 'SCHEMA'
and name like '%CUR%'
and type = 'T'
) st
ON st.[name] = ft.[tablename]
You can try
DECLARE #tableName VARCHAR(50);
SELECT #tableName = main
FROM xyx
EXEC('SELECT * FROM ' + 'dbo.' + #tableName)
Dont forget to add validation if #tableName doesnt get populated
Related
I'm creating an update statement that generate SHA256 for table columns based on table's name
1st Step: I created a procedure that get the table columns, concatenate it all in one columns, then format to a desired format.
-- Procedure code : Extract table's columns list, concatenate it and format it
Create procedure SHA_PREP (in inp1 nvarchar(20))
as
begin
SELECT concat(concat('hash_sha256(',STRING_AGG(A, ', ')),')') AS Names
FROM (
SELECT concat('to_varbinary(IFNULL("',concat(COLUMN_NAME,'",''0''))')) as A
FROM SYS.TABLE_COLUMNS
WHERE SCHEMA_NAME = 'SCHEMA_NAME' AND TABLE_NAME = :inp1
AND COLUMN_NAME not in ('SHA')
ORDER BY POSITION
);
end;
/* Result of this procedures :
hash_sha256(
to_varbinary("ID"),to_varbinary(IFNULL("COL1",'0')),to_varbinary(IFNULL("COL2",'0')) )
*/
-- Update Statement needed
UPDATE "SCHEMA_NAME"."TABLE_NAME"
SET "SHA" = CALL "SCHEMA_NAME"."SHA_PREP"('SCHEMA_NAME')
WHERE "ID" = 99 -- a random filter
The solution by #SonOfHarpy technically works but has several issues, namely:
unnecessary use of temporary tables
overly complicated string assignment approach
use of fixed system table schema (SYS.TABLE_COLUMNS) instead of PUBLIC synonym
wrong data type and variable name for the input parameter
An improved version of the code looks like this:
create procedure SHA_PREP (in TABLE_NAME nvarchar(256))
as
begin
declare SQL_STR nvarchar(5000);
SELECT
'UPDATE "SCHEMA_NAME"."TABLE_NAME" SET "SHA"= hash_sha256(' || STRING_AGG(A, ', ') || ')'
into SQL_STR
FROM (
SELECT
'TO_VARBINARY(IFNULL("'|| "COLUMN_NAME" ||'",''0''))' as A
FROM TABLE_COLUMNS
WHERE
"SCHEMA_NAME" = 'SCHEMA_NAME'
AND "TABLE_NAME" = :TABLE_NAME
AND "COLUMN_NAME" != 'SHA'
ORDER BY POSITION
);
-- select :sql_str from dummy; -- this is for debugging output only
EXECUTE IMMEDIATE (:SQL_STR);
end;
By changing the CONCAT functions to the shorter || (double-pipe) operator, the code becomes a lot easier to read as the formerly nested function calls are now simple chained concatenations.
By using SELECT ... INTO variable the whole nonsense with the temporary table can be avoided, again, making the code easier to understand and less prone to problems.
The input parameter name now correctly reflects its meaning and mirrors the HANA dictionary data type for TABLE_NAME (NVARCHAR(256)).
The procedure now consists of two commands (SELECT and EXECUTE IMMEDIATE) that each performs an essential task of the procedure:
Building a valid SQL update command string.
Executing the SQL command.
I removed the useless line-comments but left a debugging statement as a comment in the code, so that the SQL string can be reviewed without having to execute the command.
For that to work, obviously, the EXECUTE... line needs to be commented out and the debugging line has to be uncommented.
What's more worrying than the construction of the solution is its purpose.
It looks as if the SHA column should be used as a kind of shorthand row-data fingerprint. The UPDATE approach certainly handles this as an after-thought activity but leaves the "finger-printing" for the time when the update gets executed.
Also, it takes an essential part of the table design (that the SHA column should contain the fingerprint) away from the table definition.
An alternative to this could be a GENERATED COLUMN:
create table test (aaa int, bbb int);
alter table test add (sha varbinary (256) generated always as
hash_sha256(to_varbinary(IFNULL("AAA",'0'))
, to_varbinary(IFNULL("BBB",'0'))
)
);
insert into test (aaa, bbb) values (12, 32);
select * from test;
/*
AAA BBB SHA
12 32 B6602F58690CA41488E97CD28153671356747C951C55541B6C8D8B8493EB7143
*/
With this, the "generator" approach could be used for table definition/modification time, but all the actual data handling would be automatically done by HANA, whenever values get changed in the table.
Also, no separate calls to the procedure will ever be necessary as the fingerprints will always be current.
I find a solution that suits my need, but maybe there's other easier or more suitable approchaes :
I added the update statement to my procedure, and inserted all the generated query into a temporary table column, the excuted it using EXECUTE IMMEDIATE
Create procedure SHA_PREP (in inp1 nvarchar(20))
as
begin
/* ********************************************************** */
DECLARE SQL_STR VARCHAR(5000);
-- Create a temporary table to store a query in
create local temporary table #temp1 (QUERY varchar(5000));
-- Insert the desirable query into the QUERY column (Temp Table)
insert into #temp1(QUERY)
SELECT concat('UPDATE "SCHEMA_NAME"."TABLE_NAME" SET "SHA" =' ,concat(concat('hash_sha256(',STRING_AGG(A, ', ')),')'))
FROM (
SELECT concat('to_varbinary(IFNULL("',concat(COLUMN_NAME,'",''0''))')) as A
FROM SYS.TABLE_COLUMNS
WHERE SCHEMA_NAME = 'SCHEMA_NAME' AND TABLE_NAME = :inp1
AND COLUMN_NAME not in ('SHA')
ORDER BY POSITION
);
end;
/* QUERY : UPDATE "SCHEMA_NAME"."TABLE_NAME" SET "SHA" =
hash_sha256(to_varbinary("ID"),to_varbinary(IFNULL("COL1",'0')),to_varbinary(IFNULL("COL2",'0'))) */
SELECT QUERY into SQL_STR FROM "SCHEMA_NAME".#temp1;
--Excuting the query
EXECUTE IMMEDIATE (:SQL_STR);
-- Dropping the temporary table
DROP TABLE "SCHEMA_NAME".#temp1;
/* ********************************************************** */
end;
Any other solution or improvement are well welcomed
Thank you
Environment: Db2 for i, version 7.3
Library/table structure:
CORPORATE/TENANTS
LIB01/INVOICE
LIB02/INVOICE
LIB03/INVOICE
…
LIBxx/INVOICE
The CORPORATE/TENANTS table contains a list of libraries where information about each tenant is stored. It has this structure and data:
CREATE OR REPLACE TABLE TENANTS (
ID BIGINT GENERATED ALWAYS AS IDENTITY (START WITH 1),
TENANT CHAR(10) NOT NULL,
PRIMARY KEY(ID)
) RCDFMT TENANTSR;
RUNSQLSTM SRCFILE(HILLB/QDDLSRC) SRCMBR(TENANTS) DFTRDBCOL(CORPORATE)
+--+------+
|ID|TENANT|
+--+------+
| 1|LIB01 |
| 2|LIB02 |
|..|......|
|99|LIB99 |
+--+------+
The LIBxx/INVOICE tables are all identical to each other and have this structure:
CREATE OR REPLACE TABLE INVOICE (
ID BIGINT GENERATED ALWAYS AS IDENTITY (START WITH 1),
PAYDAT INTEGER(6,0) NOT NULL,
AMOUNT DECIMAL(15,2) NOT NULL DEFAULT 0,
PRIMARY KEY(ID)
) RCDFMT INVOICER;
+--+------+------+
|ID|PAYDAT|AMOUNT|
+--+------+------+
| 1|180701|100.00|
| 2|180801| 35.00|
|..|......|......|
+--+------+------+
I want to generate a list of invoice amounts for all tenants for a given date:
180701 LIB01 100.00
180701 LIB02 140.00
180701 LIB03 74.00
…
Conceptually what I want to do is this (yes, I know this is invalid SQL):
SELECT PAYDAT, TENANT, AMOUNT
FROM $X.INVOICE
WHERE PAYDAT = 180701;
I want to pull data from the INVOICE table for each TENANT but I know the FROM clause cannot be dynamic like this. I’m sure this kind of query has a name but I don’t know what it is so I’m unable to effectively use a search engine to find what I need.
This would be trivial to solve with an RPGLE program but I need a pure SQL solution.
Please note - the LIBxx values CANNOT be hardcoded in any way. These values can change at any time.
To do what you want, you can use a stored procedure with an EXECUTE IMMEDIATE in a loop to build a result set. Something like this:
Note: this is not a complete cut and paste solution, but you can modify it to do what you want.
CREATE OR REPLACE PROCEDURE GETINVOICEAMOUNTS ( )
DYNAMIC RESULT SETS 1
LANGUAGE SQL
NOT DETERMINISTIC
MODIFIES SQL DATA
CALLED ON NULL INPUT
SET OPTION COMMIT = *NONE
BEGIN
DECLARE STMT VARCHAR(1024);
DECLARE RECORD_FOUND INTEGER DEFAULT 1;
DECLARE LIBRARY CHAR(10);
DECLARE C1 CURSOR FOR
SELECT TENANT FROM CORPORATE/TENANT;
DECLARE C2 CURSOR WITH RETURN FOR
SELECT * FROM SESSION.TMP ;
DECLARE CONTINUE HANDLER FOR NOT FOUND
SET RECORD_FOUND = 0;
DECLARE GLOBAL TEMPORARY TABLE TMP
(PAYDAT INTEGER(6,0),
TENANT CHAR(10),
AMOUNT DECIMAL(15,2))
WITH REPLACE;
OPEN C1;
LOOP
FETCH C1 INTO LIBRARY;
IF RECORD_FOUND = 0;
LEAVE LOOP;
END IF;
SET STMT = 'INSERT INTO SESSION.TMP SELECT PAYDAT, LIBRARY, AMOUNT FROM ' || RTRIM(LIBRARY) || '.INVOICE WHERE PAYDAT = 180701';
EXECUTE IMMEDIATE STMT
END LOOP;
CLOSE C1;
OPEN C2;
END;
I gave you more than I planned to. But, one specific modification you will invariably need is to parameterize the date that you want to retrieve.
This is how it works:
A global temporary table named TMP is used to collect the records to be returned in a result set. Once all the records are collected, a cursor is opened over TMP and the procedure ends. This causes the values collected in TMP to be returned as a result set.
To collect the values the CORPORATE/TENANT file is read, and the column TENANT is retrieved into the variable LIBRARY. For each record a statement is built that concatenates LIBRARY into an INSERT statement. This statement is executed which loads the record into TMP. I am using EXECUTE IMMEDIATE because I cannot use a parameter marker to replace the table reference in the INSERT statement, so a prepared statement is just extra work.
You could use UNION ALL:
SELECT sub.PAYDAT, t.TENANT, sub.AMOUNT
FROM (SELECT * FROM LIB01.INVOICE
UNION ALL
SELECT * FROM LIB02/INVOICE
...
SELECT * FROM LIB0n/INVOICE) sub
JOIN TENANTS t
ON sub.id = t.id
WHERE SUB.PAYDAT = 180701;
It is an SELECT * FROM sales + #yymm template.
EDIT:
More secure way is to create a view:
CREATE VIEW combined_invoice
AS
SELECT * FROM LIB01.INVOICE
UNION ALL
SELECT * FROM LIB02/INVOICE
...
SELECT * FROM LIB0n/INVOICE;
And query:
SELECT sub.PAYDAT, t.TENANT, sub.AMOUNT
FROM combined_invoice sub
JOIN TENANTS t
ON sub.id = t.id
WHERE SUB.PAYDAT = 180701;
Of course view should be altered after adding/removing tables.
i want to use the result of a query as an input in another query.
What might make it difficult: The variable is the schema in the database.
CREATE or replace VARIABLE myschema varchar(15) ;
set myschema = (select owner from syscat.tables where tabname = 'xyz');
select count(name) as result from myschema.USR02 where USTYP = 'A';
DROP VARIABLE myschema;
This is my last try, after i failed using declare.
But i get an error, because "myschema" is used as a string, and of course there is no schema with name "myschema". The result of the first query is not used.
If I just run the first two lines, i get the schemaname as result. Do i have to mark the variable in a special way? The goal is just the result of the query in line 3 by using the dynamic value of "myschema".
Unfortunately, you have to use dynamic SQL (forming a custom SQL query through string manipulation) if you want to deal with table, schema, or column names dynamically:
This is the basic idea:
execute immediate 'select * from ' || myschema || '.USR02';
However, you can't just run a bare select in dynamic SQL; you have to put the result in something. And the whole thing must be in a compound SQL block. So the full example would look something like this (simplified query for space).
This query assumes that a table called "result" exists to store the result you are returning.
begin
declare myschema varchar(100) default '';
set myschema = (select owner from syscat.tables where tabname = 'xyz');
execute immediate 'insert into result select count(*) from ' || myschema || '.USR02';
end
select * from result;
Note that within the block, you can simply declare a variable (as shown in my example). So you don't have to declare a global variable for this purpose, unless you want it to persist beyond this one statement.
I have a Table in my Database Which have name of all the Database of my Server
Table Look like
create Table #db_name_list(Did INT IDENTITY(1,1), DNAME NVARCHAR(100))
INSERT INTO #db_name_list
SELECT 'db_One ' UNION ALL
SELECT 'db_Two' UNION ALL
SELECT 'db_Three' UNION ALL
SELECT 'db_four' UNION ALL
SELECT 'db_five'
select * from #db_name_list
I have so many SP in my Database..Which uses multiple table and Join Them..
At Present I am using the SQL code like
Select Column from db_One..Table1
Left outer join db_two..Table2
on ....some Condition ....
REQUIREMENT
But I do not want to HARDCODE the DATABASE Name ..
I want store DataBase name in Variable and use that .
Reason :: I want to restore same Database with Different name and want to Run those SP..At Present we Cant Do ,Because I have used db_One..Table1
or db_two..Table2
I want some thing like ...
/SAMPLE SP/
CREATE PROCEDURE LOAD_DATA
AS
BEGIN
DECLARE #dbname nvarchar(500)
set #dbname=( SELECT DNAME FROM #db_name_list WHERE Did=1)
set #dbname2=( SELECT DNAME FROM #db_name_list WHERE Did=2)
PRINT #DBNAME
SELECT * FROM #dbname..table1
/* or */
SELECT * FROM #dbname2.dbo.table1
END
i.e using Variable Instead of Database name ..
But it thow error
"Incorrect syntax near '.'."
P.S This was posted by some else on msdn but the answer there was not clear & I had the same kind of doubt. So please help
You can't use a variable like this in a static sql query. You have to use the variable in dynamic sql instead, in order to build the query you want to execute, like:
DECLARE #sql nvarchar(500) = 'SELECT * FROM ' + #dbname + '.dbo.mytable'
EXEC(#sql);
There seem to be a couple of options for you depending on your circumstances.
1. Simple - Generalise your procedures
Simply take out the database references in your stored procedure, as there is no need to have an explicit reference to the database if it is running against the database it is stored in. Your select queries will look like:
SELECT * from schema.table WHERE x = y
Rather than
SELECT * from database.schema.table WHERE x = y
Then just create the stored procedure in the new database and away you go. Simply connect to the new database and run the SP. This method would also allow you to promote the procedure to being a system stored procedure, which would mean they were automatically available in every database without having to run CREATE beforehand. For more details, see this article.
2. Moderate - Dynamic SQL
Change your stored procedure to take a database name as a parameter, such as this example:
CREATE PROCEDURE example (#DatabaseName VARCHAR(200))
AS
BEGIN
DECLARE #SQL VARCHAR(MAX) = 'SELECT * FROM ['+#DatabaseName+'].schema.table WHERE x = y'
EXEC (#SQL)
END
This is my first time posting on SO, so please go easy!
I'm attempting to write a SQL script that queries the same table for a list of databases in a single SQL Server instance.
I have successfully queried the list of databases that I required using the following, and inserting this data into a temp table.
Select name Into #Versions
From sys.databases
Where name Like 'Master%'
Master is suffixed with numerical values to identify different environments.
Select * From #Versions
Drop Table #Versions
The table name I am trying to query, is the same in each of the databases, and I want to extract the newest value from this table and insert it into the temp table for each of the database names returned.
I have tried researching this but to no avail. I am fairly comfy with SQL but I fear I could be out of my depth here.
You can do the following. Once you have the list of your databases, you can build up the query (you need to edit it for your purpose).
Select name Into #Versions
From sys.databases
Where name Like 'test%'
declare #sql as varchar(max) = ''
select #sql = #sql + 'INSERT INTO sometable SELECT TOP 1 * FROM ' + name + '..sourcetable ORDER BY somedate DESC; '
FROM #Versions
exec (#sql)
Drop Table #Versions
Look at The undocumented sp_MSforeachdb procedure and here