I'm using Microsoft SQL Server and it seems that I cannot get around this issue.
I have a table on which I will have some dynamic and static columns.
Static columns would be name of product, type of product and the dynamic data would be some production data from ongoing months.
At the every beginning of the month I have to drop from the dynamic columns the past month and add a new month to the end of the table
My solution was saving the name of the column into a local variable and then adding it to the alter statement. But this does not work , it keeps giving me a error as under:
Msg 102, Level 15, State 1, Line 18
Incorrect syntax near '#month_b'
I will now add the queries
declare #month_t char(15)
declare #month_b char(15)
declare #sql char(30)
set #month_b = (SELECT top 1 name
FROM sys.columns
WHERE object_id = OBJECT_ID('dbo.ct_test')
AND name != 'TTNR' AND name != 'Family' AND name like '%B%'
ORDER BY name ASC)
set #month_t = (SELECT top 1 name
FROM sys.columns
WHERE object_id = OBJECT_ID('dbo.ct_test')
AND name != 'TTNR' AND name != 'Family' AND name like '%T%'
ORDER BY name ASC)
alter table ct_test
drop column #month_b
I cannot find a solution to this, can you help me.
Thank you in advance
You need to use Dynamic Query
Declare #sql nvarchar(max)
set #sql = 'alter table ct_test drop column '+ #month_b
Exec sp_executesql #sql
set #sql = 'alter table ct_test drop column '+ #month_t
Exec sp_executesql #sql
Related
I have dynamically created tables, like XXX_JOURNAL.
Where XXX - is table prefix (variable), and _JOURNAL - is constant in table name.
I need create UPDATE trigger on database, not on particular table, and use table name (prefix) as variable:
CREATE TRIGGER triggerName ON %_JOURNAL
FOR UPDATE
AS
UPDATE XXX_JOURNAL
SET COMPANY_ID = LEFT(tableName,3) //tableName = current table (XXX_JOURNAL)
WHERE ID = ID FROM inserted
So here I have two difficulties:
How to create one trigger for all tables LIKE %_JOURNAL?
How to use table name as the keyword for current table?
I know there are a lot of mistakes in syntax. For example, I cannot use '%_JOURNAL' as table name on trigger creation. It's just for explanation, that I need create one trigger for all dynamically created tables in future.
Any ideas?
You can use stored procedure with dynamic SQL:
CREATE PROCEDURE TriggerCreationForJournals
#XXX as nvarchar(3)
AS
BEGIN
DECLARE #sql nvarchar(max),
#triggerName nvarchar(max) = #XXX + N'_JOURNAL_UPDATE',
#objectCheck int,
#checkSQL nvarchar(max),
#params nvarchar(max) = N'#objectCheck int OUTPUT'
SELECT #checkSQL = N'SELECT #objectCheck = OBJECT_ID(N'''+#triggerName+''')'
EXEC sp_executesql #checkSQL, #params, #objectCheck = #objectCheck OUTPUT
IF #objectCheck IS NULL
BEGIN
SELECT #sql = N'
CREATE TRIGGER '+QUOTENAME(#triggerName)+' ON ['+#XXX+'_JOURNAL]
FOR UPDATE
AS
UPDATE x
SET COMPANY_ID = '''+#XXX+'''
FROM ['+#XXX+'_JOURNAL] x
INNER JOIN inserted i
ON i.ID = x.ID'
EXEC sp_executesql #sql
END
ELSE
BEGIN
PRINT 'Trigger '+QUOTENAME(#triggerName)+' already exists'
END
END
Then run this:
DECLARE #sql nvarchar(max)
SELECT #sql = (
SELECT 'EXEC TriggerCreationForJournals '''+LEFT([name],3) +''';' +CHAR(10)
FROM sys.tables
WHERE [name] LIKE '%JOURNAL'
FOR XML PATH('')
)
EXEC sp_executesql #sql
To create triggers for all tables.
In #sql there will be query like:
EXEC TriggerCreationForJournals 'AFG';
EXEC TriggerCreationForJournals 'DFG';
The purpose of stored procedure is to check if trigger on table exists - if so skip its creation, you can modify the SP to drop them if exists.
The second part is a creation of script and running the SP for all tables you need.
Hope, this answer helps you with your questions.
So, a little backstory on this one:
I have a lengthy query that I use frequently for my jobs that utilizes the sp_MSForEachDB stored proc. The query creates a temporary table, and then goes through and searches sys.tables, and if a database has a table called T_Study, it will run the query and pull these results into the temporary table.
What I am now trying to do is join in another table from another database, and this database is of a different type. These database are all distinguished by the existence T_BatchStores. All databases that have a T_BatchStores table will also have a table dbo.T_TSyntax, and this is the table on which I will need to join.
Essentially, I am trying to build a universal query that I can run on any server containing this software, and I have these few universal tables, but the names of the databases themselves will vary.
So what I want to do is, in my query that populates my temporary table, add the following:
JOIN '+#MEDDB+'.dbo.T_TSyntax and then my ON clause, etc. Keep in mind that this join occurs within my begin and end clauses and that sp_MSforEachDb will be run on this.
I want #MEDDB to be just a randomly selected name of ANY database on their SQL instance that contains a T_BatchStores table - it does not matter what the name is - I just don't want to modify the query every time I run it.
How can I use my DECLARE #MEDDB and SET/SELECT #MEDDB to work with these requirements?
Also, in some reading, I read that I should use SYSNAME as the data type, but I also know NVARCHAR would work - but I'd just like a tip on which would be ideal.
I have tried the following:
DECLARE #MEDDB SYSNAME
SET #MEDDB = (SELECT TOP 1 name FROM sys.databases WHERE EXISTS (SELECT name FROM sys.tables WHERE name = '''T_BATCHSTORES'''))
SELECT #MEDDB
But this returns 1 row with a NULL value. I'm very much a beginner to SQL, so any assistance would be greatly appreciated!
Note: I am only using Microsoft SQL Server 2008 and 2012 at the present time.
Thanks!
Okay, after heavily modifying the query so that the names aren't actually exactly the same as our actual table structure, here is a slimmed-down version of the query I'm using so that you'll see what I'm going for:
/* Add or change variables as needed and comment back in WHERE statements in Insert section as needed.
You do not need to delete any variables in this section, even if you do not need them.
Simply comment in or out relevant data in the WHERE clause in Section 4. */
/* Section 1: Declaring variables. */
DECLARE #STUID NVARCHAR (65)
DECLARE #IMUID NVARCHAR (200)
DECLARE #ACCN NVARCHAR (100)
DECLARE #MEDDB NVARCHAR (255)
/* Section 2: Assigning values to variables such as an Image file's UID. */
SET #STUID = 'enterSTUID'
SET #IMUID = 'enterIMUIDhere'
SET #ACCN = 'enterACCNhere'
SET #MEDDB = (SELECT TOP 1 name FROM sys.databases WHERE [name] LIKE '%med%'
AND [name] NOT LIKE '%audit%')
/* Section 3: Creating our temporary table to dump our results. */
IF OBJECT_ID('tempdb.dbo.#tempBatchResultsD6') IS NULL
BEGIN
CREATE TABLE #tempBatchResultsD6
(
Database_Name VARCHAR (200),
THING1 VARCHAR(100) NOT NULL,
THING2 VARCHAR(200) NOT NULL,
THING3 DATETIME NOT NULL,
TSyntaxUID VARCHAR (66) NOT NULL,
TSyntaxDesc VARCHAR (128) NOT NULL
)
END
TRUNCATE TABLE #tempBatchResultsD6
/* Section 4: Query that will be used to populate the contents of the temporary table created above.
Utilizing the stored procedure "sp_MSForEachDb," this will search every database on the SQL instance.
Here, we are limiting our results to only searching specific databases by only returning results from databases that have a "T_Studies" table. */
DECLARE #Command NVARCHAR(MAX)
SET #Command = N'USE [?];
IF EXISTS (SELECT * FROM sys.tables WHERE [name] = ''T_Studies'')
BEGIN
INSERT #tempBatchResultsD6
SELECT
DB_Name () as Database_Name,
THING1,
THING2,
THING3,
TS.TSyntaxUID,
TS.TSyntaxDesc
FROM T_Studies ST WITH (nolock)
JOIN T_Patients PT WITH (nolock) ON ST.ST_PT_FOLDERID = PT.PT_FOLDERID
JOIN T_Series SE WITH (nolock) ON ST.ST_FOLDERID = SE.SE_ST_FOLDERID
JOIN T_Images IM WITH (nolock) ON SE.SE_FOLDERID = IM.IM_SE_FOLDERID
JOIN '+#MEDDB+'.dbo.T_TSyntaxes TS WITH (nolock) on IM.IM_TSyntaxID = TS.TSyntaxUID
WHERE ST.STUID = '''+#STUID+'''
--WHERE IM.IM_UID = '''+#IMUID+'''
--WHERE ST.ST_ACCNNO = '''+#ACCN+'''
END'
EXEC sp_MSForEachDb #Command
/* Section 5: Querying our temporary table to get our results. */
SELECT
Database_Name,
THING1,
THING2,
THING3,
TSyntaxUID,
TSyntaxDesc
FROM #tempBatchResultsD6
ORDER BY Database_Name
So as you can see, this is a massive temp table that will pull from all databases that have a T_Studies table in them. It's huge in its actual form, but this is trimmed down significantly.
The problem comes in section 2, where I am using #MEDDB to choose a random database name if the name contains the word "Med" but not the word "audit." This is problematic because it assumes consistent naming across all sites - and while these names are suggested, they are never a guarantee.
To guarantee consistency, I am trying to populate the #MEDDB variable with the name of ANY database on their system that contains a T_BatchStores table instead of the WHERE [name] like portion.
Any advice with this new info would be greatly appreciated!
I am not sure whether I understand your question completely.
But if you wanna loop through all databases, you can use something like the following code. "SELECT XXX" would then be your query, by using "use ' + #DB_Name + ';" you switch to the desired database to execute the your query.
DECLARE #DB_Name varchar(100)
DECLARE #Command nvarchar(max)
DECLARE database_cursor CURSOR FOR
SELECT name
FROM MASTER.sys.sysdatabases
OPEN database_cursor
FETCH NEXT FROM database_cursor INTO #DB_Name
WHILE ##FETCH_STATUS = 0
BEGIN
set #Command =
'
use ' + #DB_Name + ';
SELECT XXX
'
EXEC sp_executesql #Command
FETCH NEXT FROM database_cursor INTO #DB_Name
END
CLOSE database_cursor
DEALLOCATE database_cursor
DECLARE #MEDDB NVARCHAR(500)
SET #MEDDB = 'SELECT TOP 1 name FROM sys.databases WHERE EXISTS (SELECT name FROM sys.tables WHERE name = ''T_BATCHSTORES'')'
EXEC (#MEDDB)
This is Dynamic SQL. Of course, I'm not getting any results, either, but I'm not in your database. Still, this allows you to be 'dynamic', and use a variable to modify things:
DECLARE #MEDDB NVARCHAR(500)
DECLARE #MEDDB2 NVARCHAR(100) = 'T_BATCHSTORES'
SET #MEDDB = 'SELECT TOP 1 name FROM sys.databases WHERE EXISTS (SELECT name FROM sys.tables WHERE name = ''' + #MEDDB2 + ''')'
EXEC (#MEDDB)
My recommendation is that you run simpler queries that show what you want, and then you build them into the dynamic method.
For instance, I'm in AdventureWorks right now, so I can do:
SELECT * FROM sys.databases
This gives me a list of all the databases that are available in here.
So maybe I expand that to
SELECT * FROM sys.databases WHERE name = 'AdventureWorks'
This gives me just one line of results. So if that's what I want, I build it into the dynamic portion:
DECLARE #MEDDB NVARCHAR(500)
DECLARE #MEDDB2 NVARCHAR(100) = 'AdventureWorks'
SET #MEDDB = 'SELECT * FROM sys.databases WHERE name =''' + #MEDDB2 + ''''
EXEC (#MEDDB)
It just all depends what you're looking for. I always find the data I want first, and then figure out how to make my query look for it.
There is this query that I keep using over and over:
SELECT column_name, count(column_name) FROM table_name GROUP by column_name ORDER BY COUNT(column_name) DESC
I use this to check which different values there are in a column and how often they occur.
Because I use this query so often and it's repeating the same 4 times: column_name, I was like: why not make a stored procedure:
CREATE PROCEDURE countcv #table_name VARCHAR(50),#column_name VARCHAR(50)
AS
BEGIN
SELECT #column_name,COUNT(#column_name) FROM #table_name GROUP BY #column_name ORDER BY COUNT(#column_name)
END
Here is where I get stuck, I can not manage to get a variable tablename:
Must declare the table variable "#table_name"
I believe that #Julien Vavasseur and #Dark Knight has already addressed to your question.
However, I would like to add here that, Sql Server 2008 introduced Table-Valued Parameter by using which we can pass table type variable to the stored procedures. e.g.
Assuming you have a table by the name tblTest with the below columns
ID INT,
Name VARCHAR(50)
Step 1: Declare a new table User Defined Type
CREATE TYPE tblTestType AS TABLE
(
ID INT,
Name VARCHAR(50)
)
Step 2: Create a STORED PROCEDURE that has tblTestType as parameter
CREATE PROCEDURE countcv
(
#tblName tblTestType readonly
)
AS
INSERT INTO tblTest (ID, Name)
SELECT ID, Name
FROM
#tblName;
Then you can use DataTable (if you are using C#) and pass this data table as a parameter to the Stored Procedure.(you can find an example in the link I provided).
There is no way to do it directly. You need to use dynamicSQL approach. Assuming you pass correct table and column names. Below one should work.
CREATE PROCEDURE countcv #table_name VARCHAR(50),#column_name VARCHAR(50)
AS
BEGIN
declare #SQL nvarchar(max)
set #SQL = 'SELECT '+#column_name+',COUNT('+#column_name+')
FROM '+#table_name+'
GROUP BY '+#column_name+'
ORDER BY COUNT('+#column_name+')'
EXEC sp_executesql #SQL
END
If you want to do something like this, you must use dynamic SQL:
CREATE PROCEDURE countcv #table_name sysname, #column_name sysname
AS
BEGIN
Declare #sql nvarchar(max)
Set #sql = 'SELECT ' + QUOTENAME(#column_name)+', COUNT(' + QUOTENAME(#column_name)+')
FROM ' + QUOTENAME(#table_name)+'
GROUP BY ' + QUOTENAME(#column_name)+' ORDER BY COUNT(' + QUOTENAME(#column_name)+')'
EXEC sp_executesql #sql
END
Use sysname for data type for column and table names (buitin datatype for object names, alias to nvarchar(128))
Use QUOTENAME to add delimeter to column and table names
In my SQL database, I would like to make a general purpose soft link table. Perhaps something similar the following:
create table soft_link(
id uniqueidentifier,
name varchar(255),
LINK uniqueidentifier,
TABLE varchar(255),
primary key(id));
Say I have object "b_object" in some other table in the database. The LINK column would be the the unique identifier of b_object, and TABLE would be the table in which b_object is stored within the database.
Now I want to make a single stored procedure "sp_ResolveSoftLink". This method will take an id of a soft link, look up the LINK and TABLE columns of the soft link, and then use the TABLE and LINK to query for b_object.
The following is NOT proper SQL syntax, but hopefully it helps illustrate my question. I want to combine these two queries into a single stored procedure and return the result of the second query:
select LINK, TABLE from soft_link where id = xxxxxx
select * from TABLE where id = LINK
-- return the result of the second select query
FUNDAMENTAL QUESTION: How/can I use the varchar return from one query to form another query in the same stored procedure in SQL?
You can create a Stored procedure like this.
Here, First you have to store value of LINK and Table in variable and then use these variable to form another Dynamic Query
CREATE PROC spName
#id INT
AS
BEGIN
Declare #LINKValue uniqueidentifier, #TABLE varchar(255),#SQL varchar(max)
SELECT #LINKValue = LINK , #TABLE = TABLE
FROM soft_link
WHERE soft_link id = #id
SET #SQL='SELECT * FROM';
SET #SQL = #SQL +' ' + #TABLE
SET #SQL = #SQL +' ' + 'WHERE ID =' +' ' + #LINKValue
PRINT #SQL -- SEE Here This is what you actually Want
--EXEC (#SQL) --Then Execute this
END
I have a SQL Server table which has 625 columns created with different datatypes like int, varchar(25), decimal(18, 2), etc...
Now am interested in changing datatype of all columns to varchar(255). Instead of executing below query for all the columns one by one, is there a single SQL Server query to change datatypes of all columns in a table at one shot?
ALTER TABLE dbo.Employee
ALTER COLUMN FirstName VARCHAR(255) NOT NULL
Looking forward for your response.
There is no one single "magic" bullet to do this - it's an operation that's rather unusual, so it's not supported natively.
What you can do is iterate over the columns of your table from the system catalog views, create such an ALTER statement on the fly, and also execute it - something like this:
DECLARE AlterTableCursor CURSOR FAST_FORWARD
FOR
SELECT
AlterCmd = 'ALTER TABLE dbo.YourTableNameHere ALTER COLUMN ' + name + ' VARCHAR(255) NULL'
FROM
sys.columns
WHERE
object_id = OBJECT_ID('dbo.YourTableNameHere')
DECLARE #AlterTableCmd NVARCHAR(200)
OPEN AlterTableCursor
FETCH NEXT FROM AlterTableCursor INTO #AlterTableCmd
WHILE ##FETCH_STATUS = 0
BEGIN
EXEC (#AlterTableCmd)
FETCH NEXT FROM AlterTableCursor INTO #AlterTableCmd
END
CLOSE AlterTableCursor
DEALLOCATE AlterTableCursor
Replace the YourTableNameHere with your actual table name - and you should be good to go! Test this on a copy of your live data first !
is not possible. You will need to do this one by one. You can do following things -
You can create a Temporary Table with your desired columns and type.
copy the data from original table to temporary table.
delete original table
Rename you Temporary Table to your original name
I would say that it's not a good design to have 625 columns in one table, but you do what ever you have been asked to do.
You could generate a SQL string that contains multiple ALTER statements and execute it with EXEC. You have to be careful with the data conversion though. This is why it's probably better to do it in a cursor, because you can catch possible exceptions for the columns that cannot be altered. Here is a simple code which does it in two steps:
generate the SQL string;
execute it using EXEC
Code sample:
SELECT * FROM sys.columns WHERE OBJECT_NAME(object_id) = 'Employee'
DECLARE #SQL VARCHAR(MAX)
SET #SQL = (
SELECT '
ALTER TABLE dbo.Employee ALTER COLUMN ' + c.name + ' VARCHAR(255) NULL;
'
FROM sys.columns c WHERE OBJECT_NAME(object_id) = 'Employee'
FOR XML PATH(''), TYPE
).value('text()[1]', 'VARCHAR(MAX)')
PRINT #SQL
EXEC(#SQL)
SELECT * FROM sys.columns WHERE OBJECT_NAME(object_id) = 'Employee'