I am trying to figure out the best method to insert column names held in Table1 into a SELECT statement running against Table2. This query is running in a stored procedure. That doesn't do a very good job of explaining, so lets say I had these values in Table1:
What I am trying to do is use these column names in the SELECT statement against Table2:
Select -- Column Names
from Table2
where UserId = 3;
I'm not sure if an input parameter could be used in that way or how to pass the values into it. For example:
Select #ColumnNames
from Table2
where UserId = 3;
Or maybe a join to table 2?
Thanks!
You will have to use Dynamic SQL
declare #columns varchar(1000)
declare #sql varchar(8000)
select #columns='', #sql=''
select #columns=#columns+value+',' from table1
set #columns=left(#columns,len(#columns)-1)
set #sql='select '+#columns+' from table2'
exec(#sql)
But beware of SQL Injection and read www.sommarskog.se/dynamic_sql.html
You could query the system tables to get the column(s) i.e. (take out WHERE clause to see all the tables and columns)
SELECT tab.name AS TableName,
col.name AS ColName,
tp.name AS SType,
col.max_length,
col.[precision],
(CASE col.is_nullable
WHEN 1 THEN 'true'
WHEN 0 THEN 'false'
ELSE 'unknown'
END) AS Is_Nullable
FROM sys.tables as tab
LEFT OUTER JOIN sys.columns AS col
ON tab.object_id = col.object_id
LEFT OUTER JOIN sys.types AS tp
ON col.system_type_id = tp.system_type_id
WHERE tab.name = 'Table1'
ORDER BY tab.name,col.name
Related
I'm building a package in SSIS that first acquires source data from from another server and loads into my server. From there I have another package that manipulates this source data and loads a new table.
I want to prevent this 'manipulation' package from running if something failed on my 'source' package. I can talk it out but not Syntax it out...
If MyTABLE exists and count(*) from MyTABLE > 0 then 'GOOD' else 'BAD' I was going to have a constraint that wouldn't run the rest of the package if anything came back bad. If this is an asinine way of achieving this then please show me the easier way to achieve this.
The ultimate goal would be to have a list of 'GOOD' or 'BAD' and the table name as the next column so if anything fails I can get an email of my query that would quickly show me what is bad and what is good.
Source_Check Source_Table
GOOD TABLE1
BAD TABLE2
GOOD TABLE3
etc.....
my issue is I get an error trying to count(*) from a table that doesn't exist... Not sure how to overcome this :(
There are probably easier ways to go about this, I'm just a newb is all. Could phrase my search right to get any results from google.
Metadata is going to be your friend. Assuming SQL Server, you can write a simple query like
SELECT
*
FROM
sys.schemas AS S
INNER JOIN sys.tables AS T
ON T.schema_id = S.schema_id
WHERE
S.name = N'dbo'
AND T.name = N'SomeTable';
If that returns a result, then you know your table exists.
The problem with SELECT COUNT(*) is that the table must exist. It also locks forces you to crawl the table. There are tricks for addressing this but my favorite is to go back to the metadata well. Look at this query. It's going to generate a list of all the tables and their row counts in no time at all.
SELECT
s.[Name] as [Schema]
, t.[name] as [Table]
, SUM(p.rows) as [RowCount]
FROM
sys.schemas s
LEFT OUTER JOIN
sys.tables t
ON s.schema_id = t.schema_id
LEFT OUTER JOIN
sys.partitions p
ON t.object_id = p.object_id
LEFT OUTER JOIN
sys.allocation_units a
ON p.partition_id = a.container_id
WHERE
p.index_id in(0,1) -- 0 heap table , 1 table with clustered index
AND p.rows is not null
AND a.type = 1 -- row-data only , not LOB
GROUP BY
s.[Name]
, t.[name]
ORDER BY
1
, 2
Now you can compare that resultset to your list of tables that may or may not exist.
You could try something like this:
DECLARE #SourceTables TABLE (tbl_name VARCHAR(100))
INSERT INTO #SourceTables VALUES('TABLE1'),('TABLE2'),('TABLE3');
WITH CTE
AS
(
SELECT o.name AS tbl_name,
i.[Rows] AS row_count
FROM sysindexes i
INNER JOIN sysobjects o
ON i.id = o.id
WHERE i.IndId < 2
AND xtype = 'U'
)
--Returns tables that don't exist
SELECT CASE
WHEN B.tbl_name IS NULL AND B.row_count > 0 --when there is no table and row count is greater than 0, then good
THEN 'Good'
ELSE 'Bad'
END AS Source_Check,
A.tbl_name
FROM #SourceTables A
LEFT JOIN CTE B
ON A.tbl_name = B.tbl_name
Theoretical Results:
Source_Check tbl_name
------------ -------------------------
Good TABLE1
Good TABLE2
Bad TABLE3
I assume you're using SQL Server based on the SSIS package. You could simplify things using OBJECT_ID Try Something Like the following....
CREATE TABLE #OUTPUT(Source_Check VARCHAR(10), Source_Table VARCHAR(10))
IF OBJECT_ID('DBNAME.dbo.Table1') IS NOT NULL
BEGIN
INSERT INTO #OUTPUT VALUES ('GOOD', 'TABLE1')
END
ELSE
INSERT INTO #OUTPUT VALUES ('BAD', 'TABLE1')
END
IF OBJECT_ID('DBNAME.dbo.Table2') IS NOT NULL
BEGIN
INSERT INTO #OUTPUT VALUES ('GOOD', 'TABLE2')
END
ELSE
INSERT INTO #OUTPUT VALUES ('BAD', 'TABLE2')
END
IF OBJECT_ID('DBNAME.dbo.Table3') IS NOT NULL
BEGIN
INSERT INTO #OUTPUT VALUES ('GOOD', 'TABLE3')
END
ELSE
INSERT INTO #OUTPUT VALUES ('BAD', 'TABLE3')
END
SELECT * FROM #OUTPUT
We have a legacy application which created multiple tables with the following naming convention: table_20140618, table_20140623, etc where the date is when the program run. I am trying to clean up the database now, and drop some of these tables.
In each table there are two fields: DateStarted and DateFinished. I want to select the tables (and then drop them) where DateStarted has value and DateFinished is NOT null.
At the moment I am using the following query to select all the tables that start with 'table_'
such as:
Select (TABLE_NAME) FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_TYPE = 'BASE TABLE'
AND TABLE_NAME LIKE 'table_%';
I am not sure how to get all the tables together by searching within their fields. I could do it through the code, but that should mean multiple hits on the database. Any ideas?
Made this after my first comment above, but you should be able to alter the code to fit your specs. Basically, this will use dynamic SQL to generate the commands based on your filters and conditions. So you can use whatever conditions you want in the SELECT #SQL = ... part, to check for the dates, and then add the table name when the conditions are met.
The script returns a list with tablenames and the drop command, so you can check what you're doing before you do it. But from there you can just copy the drop command list and execute it if you want.
IF OBJECT_ID('tempdb..#TABLES') IS NOT NULL
DROP TABLE #TABLES
CREATE TABLE #TABLES (ROWNMBER INT IDENTITY(1,1), TABLENAME VARCHAR(256) COLLATE DATABASE_DEFAULT)
/*
-- Old code to fetch ALL tables with specified name
INSERT INTO #TABLES
SELECT name
FROM sys.tables
WHERE name LIKE 'table[_]%'
*/
-- Updated code to fetch only those tables which contain the DateStarted and DateFinished columns
INSERT INTO #TABLES
SELECT TAB.name
FROM sys.tables TAB
LEFT JOIN sys.columns C1 on C1.object_id = TAB.object_id
AND C1.name = 'DateStarted'
LEFT JOIN sys.columns C2 on C2.object_id = TAB.object_id
AND C2.name = 'DateFinished'
WHERE TAB.name LIKE 'table[_]%'
AND C1.name IS NOT NULL AND C2.name IS NOT NULL
IF OBJECT_ID('tempdb..#DROPPABLE_TABLES') IS NOT NULL
DROP TABLE #DROPPABLE_TABLES
CREATE TABLE #DROPPABLE_TABLES (TABLENAME VARCHAR(256) COLLATE DATABASE_DEFAULT)
DECLARE #ROW_NOW INT, #ROW_MAX INT, #SQL VARCHAR(MAX), #TABLENAME VARCHAR(256)
SELECT #ROW_NOW = MIN(ROWNMBER), #ROW_MAX = MAX(ROWNMBER) FROM #TABLES
WHILE #ROW_NOW <= #ROW_MAX
BEGIN
SELECT #TABLENAME = TABLENAME FROM #TABLES WHERE ROWNMBER = #ROW_NOW
SELECT #SQL =
'IF (SELECT COUNT(*) FROM '+#TABLENAME+' WHERE DateStarted IS NOT NULL) > 0
AND (SELECT COUNT(*) FROM '+#TABLENAME+' WHERE DateFinished IS NOT NULL) > 0
SELECT '''+#TABLENAME+''''
INSERT INTO #DROPPABLE_TABLES
EXEC(#SQL)
SET #ROW_NOW = #ROW_NOW+1
END
SELECT *, 'DROP TABLE '+TABLENAME DROPCOMMAND FROM #DROPPABLE_TABLES
EDIT:
As per your comment, it seems not all such tables have those columns. You can use the following script to identify said tables and which column is missing, so you can check into them further. And you can use the same idea to filter the results of the first query to only count in tables which have those columns.
SELECT TAB.name TABLENAME
, CASE WHEN C1.name IS NULL THEN 'Missing' ELSE '' END DateStarted_COL
, CASE WHEN C2.name IS NULL THEN 'Missing' ELSE '' END DateFinished_COL
FROM sys.tables TAB
LEFT JOIN sys.columns C1 on C1.object_id = TAB.object_id
AND C1.name = 'DateStarted'
LEFT JOIN sys.columns C2 on C2.object_id = TAB.object_id
AND C2.name = 'DateFinished'
WHERE TAB.name LIKE 'table[_]%'
AND (C1.name IS NULL
OR C2.name IS NULL)
Is it possible to use a set of query results for column names in a select statement?
Example, I have a table named TableA:
Column: Type:
KeyOne nvarchar(5)
KeyTwo nvarchar(5)
TableB is another table, whose column names might be stored in TableA.
Suppose TableB is like this:
Column: Type:
Val1 int
Val2 int
Is there any way I could do a query like this to get the columns?
SELECT (select TOP 1 KeyOne, KeyTwo FROM TableA)
FROM TableB
Another example using strings would be like this:
SELECT (select 'Val1', 'Val2')
FROM TableB
Is this possible in any way without concatenated SQL?
Unfortunately you can only do this with dynamic SQL, but it's pretty straightforward:
DECLARE #cols VARCHAR(MAX) = (SELECT TOP 1 KeyOne+','+KeyTwo FROM TableA)
,#sql VARCHAR(MAX)
SET #sql = 'SELECT '+#cols+' FROM TableB'
EXEC (#sql)
You can read table column names dynamically from sys.columns system views or using other management views
select name from sys.columns where object_id = object_id(N'TableName')
Then by creating a dynamic SQL query you can create your own select
I have a DataBase with around +100 tables, like half of tables have column A & column B.
My question is, Can I query all tables that have this columns with a specific values e.g.
SELECT * FROM DATABASE
WHERE
EACHTABLE HAS COLUMN A = 21 //only if table has columns and then values
AND
COLUMN B = 13
I am not sure how exact I will do it, nothing is coming up on google either
You can use the undocumented MS stored procedure sp_MSforeachtable, if you fancy living life recklessly:
create table T1 (
ColumnA int not null,
ColumnB int not null
)
go
create table T2 (
ColumnA int not null,
Column2 int not null
)
go
create table T3 (
Column1 int not null,
ColumnB int not null
)
go
create table T4 (
ColumnA int not null,
ColumnB int not null
)
go
insert into T1 values (1,2);
insert into T2 values (3,4);
insert into T3 values (5,6);
insert into T4 values (7,8);
go
create table #Results (TableName sysname,ColumnA int,ColumnB int)
exec sp_MSforeachtable 'insert into #Results select ''?'',ColumnA,ColumnB from ?',
#whereand = ' and syso.object_id in (select object_id from sys.columns where name=''ColumnA'') and syso.object_id in (select object_id from sys.columns where name=''ColumnB'')'
select * from #Results
drop table #Results
Result:
TableName ColumnA ColumnB
------------------------------------- ----------- -----------
[dbo].[T1] 1 2
[dbo].[T4] 7 8
By default, sp_MSforeachtable will, as its name implies, perform the same task for each table in the database. However, one optional parameter to this procedure, called #Whereand, can be used to modify the WHERE clause of the internal query that enumerates the tables in the database. It helps to know that this internal query has already established two aliases to some of the system views. o is an alias for sysobjects (the legacy system view). syso is an alias for sys.all_objects (a more modern system view).
Once sp_MSforeachtable has decided which tables to run against, it will execute the query given to it as its first parameter. But, it will replace ? with the schema and table name (? is the default replacement character. This can be changed as needed)
In this case, I chose to create a temp table, then have each selected table store its results into this temp table, and after sp_MSforeachtable has finished running, to select the combined results out with no further processing.
There is a similar (and similarly undocumented) procedure called sp_MSforeachdb which will access each user database on the server. These can even be combined (although you have to be careful with doubling up ' quote characters twice, at times). However, there's no equivalent sp_MSforeachcolumn.
Try this:
select t.name from sys.objects t inner join sys.columns c
on t.name=OBJECT_NAME(c.object_id)
where t.type='U'
and c.name in('col1','col2')
group by t.name
having COUNT(*) = 2
order by 1
Then you just loop through all the tables and fine the values for these columns.
Like
Declare #out TABLE(tblname varchar(100))
if exists(select * from tbl1 where col1='21' and col2='22')
BEGIN
INSERT INTO #out
select tbl1
END
You can try like this using dynamic query.
select 'select * from '+table_name+ ' where'+column_name+'=21'
from information_schema.columns where column_name = 'A'
I suggest to use two steps:
First, find out all tables in your database that have these two columns and use it for a temporal derived table. For I am not an expert in SQL-Server 2008 I recommend to have a look at the whitepages.
The expression might look like this:
SELECT tablename
FROM information_schema.tables sdbt
WHERE "column a" IN
(SELECT columns
FROM information_schema.columns col
WHERE col.tablename = sdbt.tablename)
Second, use a expresssion to filter the results according to your demanded values.
This command should do the trick in one go, only for column A, amend accordingly to include any other columns you need:
exec sp_MSforeachtable
#command1=N'SELECT * FROM ? WHERE A = 21',
#whereand=' and o.name IN (SELECT TABLE_NAME FROM INFORMATION_SCHEMA.COLUMNS WHERE COLUMN_NAME = ''A'') '
I want to find out whether the table has an identity column or not. Table is unknown to me. I have not done the structure of the table. Using Query?
I am using Sql Server Compact Edition.
IF (OBJECTPROPERTY(OBJECT_ID('TABLE_NAME'), 'TableHasIdentity') = 1)
ObjectProperty is available starting sql server 2008 Reference:
OBJECTPROPERTY
This query returns a table's identity column name:
CREATE PROCEDURE dbo.usp_GetIdentity
#schemaname nvarchar(128) = 'dbo'
,#tablename nvarchar(128)
AS
BEGIN
SELECT OBJECT_NAME(OBJECT_ID) AS TABLENAME,
NAME AS COLUMNNAME,
SEED_VALUE,
INCREMENT_VALUE,
LAST_VALUE,
IS_NOT_FOR_REPLICATION
FROM SYS.IDENTITY_COLUMNS
WHERE OBJECT_NAME(OBJECT_ID) = #tablename
AND OBJECT_SCHEMA_NAME(object_id) = #schemaname
END
Then form the code side.
Call this stored procedure using the datareader role, then check datareader.hasrows(). If the condition value is true (1), then the table has identity column if set. If not then it doesn't have an identity column.
I know it's long time ago but i found this helpful
try this :
IF EXISTS (SELECT * from syscolumns where id = Object_ID(#TABLE_NAME) and colstat & 1 = 1)
BEGIN
-- Do your things
END
Any of the below queries can be used to check if an Identity Column is present in the table
1)
SELECT *
FROM sys.identity_columns
WHERE OBJECT_NAME(object_id) = 'TableName'
2)
SELECT *
FROM sys.identity_columns
WHERE object_id = (
SELECT id
FROM sysobjects
WHERE name = 'TableName'
)
I would just like to add this option as well as I think it is the simplest
SELECT COLUMNPROPERTY(OBJECT_ID('TableName'),'ColumnName','isidentity')
One way to do this would be to make use of the stored procedure sp_help. I.e:
sp_help MyTable
This will return a DataSet that has all the information you would need on the table. There is a specific Table that has information on identities.
I.e:
If it does not contain an identity field, the Identity column will say: "No identity column defined".
#Pranay: he said Compact Edition. Stored procedures aren't supported, and there is no sys.anything.
This is the call:
SELECT Count(*) FROM INFORMATION_SCHEMA.COLUMNS WHERE AUTOINC_INCREMENT IS NOT NULL AND TABLE_NAME='this_table'
It will return either 1 (true) or 0 (false).
...
declare #tblhasIdentCol bit = IF (IDENT_CURRENT( #dbName +'.'+ #schemaName +'.'+ #tableName ) IS NOT NULL , 1 , 0 )
You get numeric value if table has identity
Very simple answer would be to run this:
SELECT IDENT_CURRENT('TABLE-NAME')
This would give max value of identity column if exists, if the column doesn't exist, it gives 1 as result.
Based on max value, you can identify which column is having that and determine the identity column.
This the query that get u all the tableNames, columnnames of the table, and is_identity or not in the selected database
SELECT
sys.columns.name
, sys.tables.name
, is_identity
FROM sys.columns
INNER JOIN sys.tables ON sys.tables.object_id = sys.columns.object_id
AND sys.columns.is_identity = 1
CREATE FUNCTION dbo.fnTableHasIdentity(#Tbl sysname)
RETURNS TINYINT
BEGIN
RETURN OBJECTPROPERTY(OBJECT_ID(#Tbl), 'TableHasIdentity')
END
--As simple as that!
select t.name as TableName,c.name as ColumnName
from sys.identity_columns c
inner join sys.tables t on c.object_id = t.object_id
where t.name = 'TableName'
If you like me, needed to be able to do this for tables in an arbitrary database, then I found the following solution:
IF EXISTS (
SELECT 1
FROM [database name].sys.identity_columns AS id_col
INNER JOIN [database name].sys.objects
ON objects.object_id = id_col.object_id
INNER JOIN [database name].sys.schemas
ON schemas.schema_id = objects.schema_id
AND schemas.name = 'schema name'
WHERE OBJECT_NAME(id_col.object_id, DB_ID('database name')) = 'table name'
) SELECT 1 ELSE SELECT 0
you can get the 1 or 0 Boolean Form if the current table has identity Columns by using this
SELECT Count(Column_ID) FROM sys.identity_columns WHERE OBJECT_NAME(object_id) = 'tableName'
One way to list all Tables with their identity column if it exists
to get you desired table add at the end of the filter "and o.name='TableName'"
where Tbale Nam is the table you are looking for
SELECT o.[Name][TableName],i.[name][IdentityColName] FROM
sys.objects o
left outer join sys.identity_columns i on i.object_id=o.object_id
where o.type='U'