I have a sql table that I am trying to add a column from another table to. Only when I execute the alter table query it does not pull the values out of the table to match the column where I am trying to make the connection.
For example I have column A from table 1 and column A from table 2, they are supposed to coincide. ColumnATable1 being an identification number and ColumnATable2 being the description.
I tried this but got an error...
alter table dbo.CommittedTbl
add V_VendorName nvarchar(200)
where v_venkey = v_vendorno
It tells me that I have incorrect syntax... Anyone know how to accomplish this?
alter table dbo.CommittedTbl
add V_VendorName nvarchar(200);
go
update c
set c.V_VendorName = a.V_VendorName
from CommittedTbl c
join TableA a
on c.v_venkey = a.v_vendorno;
go
I'm just guessing at your structure here.
alter table 2 add column A <some_type>;
update table2 set column A = (select column_A from table2 where v_venkey = v_vendorno);
Your names for tables and columns are a bit confusing but I think that should do it.
There is no WHERE clause for an ALTER TABLE statement. You will need to add the column (your first two lines), and then insert rows based upon a relationship you define between the two tables.
ALTER TABLE syntax:
http://msdn.microsoft.com/en-us/library/ms190273%28v=sql.90%29.aspx
There are several languages within SQL:
DDL: Data Definition Language - this defines the schema (the structure of tables, columns, data types) - adding a column to a table affects the table definitions and all rows will have that new column (not just some rows according to a criteria)
DML: Data Manipulation Language - this affects data within a table, and inserting, updating or other changes fall into this and you can update some data according to criteria (and this is where a WHERE clause would come in)
ALTER is a DDL statement, while INSERT and UPDATE are DML statements.
The two cannot really be mixed as you are doing.
You should ALTER your table to add the column, then INSERT or UPDATE the column to include appropriate data.
Is it possible that you want a JOIN query instead? If you want to join two tables or parts of two tables you should use JOIN.
have a look at this for a start if you need to know more LINK
hope that helps!
Related
I am writing the following query to add a column at a specified position but getting the below error:
alter table quantum_raw_dev.rpt_backup_allocation
change upt_type upt_type STRING after tray_size;
You can add one or more columns to the end of the column list using:
ALTER TABLE <table_name> ADD COLUMNS (col_name col_type, ...);
[note: there is NO comma between column name and type]
Adding or Removing Columns
You can add one or more columns to the end of the column list using ADD COLUMNS,
or (with Impala only) you can delete columns using DROP COLUMN.
The general syntax is
ALTER TABLE tablename ADD COLUMNS (col1 TYPE1,col2 TYPE2,… );
ALTER TABLE tablename DROP COLUMN colname;
For example, you can add a bonus integer column to the employees table:
ALTER TABLE employees ADD COLUMNS (bonus INT);
Or you can drop the office_id column from the employees table:
ALTER TABLE employees DROP COLUMN office_id;
Notes
DROP COLUMN is not available in Hive, only in Impala. However, see “Replacing All Columns” below.
You can only drop one column at a time.
To drop multiple columns, use multiple statements or use the method to replace columns (see below).
You cannot add a column in the middle of the list rather than at the end.
You can, however, add the column then change the order (see above) or use the method to replace columns (see below).
As with changing the column order, these do not change the data files.
If the table definition agrees with the data files before you drop any column other than the last one,
you will need to recreate the data files without the dropped column's values.
If you drop the last column, the data will still exist but it will be ignored when a query is issued.
If you add columns for which no data exists, those columns will be NULL in each row.
Replacing All Columns
You can also completely replace all the columns with a new column list.
This is helpful for dropping multiple columns,
<h1>or if you need to add columns in the middle of the list<h1>
<h2>(like your use case)<h2>
The general syntax is
ALTER TABLE tablename REPLACE COLUMNS (col1 TYPE1,col2 TYPE2,… );
This completely removes the existing list of columns and replaces it with the new list.
Only the columns you specify in the ALTER TABLE statement will exist, and they will be in the order you provide.
Note
Again, this does not change the data files, only the metadata for the table,
so you'll either want the new list to match the data files or need to recreate the data files to match the new list.
I do not think you can add columns in between columns in Impala like above.
You can backup the data, drop the and recreate with new structure, and load the table from backup. Also if you have HIVE in your system you can try to do below steps -
Add column first and then use below commands to move columns around.
ALTER TABLE tab ADD COLUMNS (id BIGINT);
This moves id column to the beginning.
ALTER TABLE tab CHANGE COLUMN id id BIGINT first;
This moves existing_col after id.
ALTER TABLE tab CHANGE COLUMN existing_col existing_col string AFTER id;
Please refresh/invalidate metadata after applying all DDLs.
You cannot add column in between. Best way is to archive the data in another table. Drop the impala old table and create a fresh table with new columns as per the desired location and then reinsert the data.
Currently I need to move three columns from table A to table B. And I am using the update join table script to copy the existing data to the new columns. Afterwards the old column at table A will be drop.
Alter table NewB add columnA integer
Alter table NewB add columnB integer
Update NewB
Set NewB.columnA = OldA.columnA, NewB.columnB = OldA.columnB
From NewB
Join OldA on NewB.ID = OldA.ID
Alter table OldA drop column columnA
Alter table OldA drop column columnB
These script will add new columns and update the existing data from the old table to the newly created columns. Then remove the old columns.
But due to system structure, I will required to run SQL Script for more than one times to makes sure the database is up to date.
Although I did If (Columns Exist) Begin (Alter Add, Update, Alter Drop) End to ensure the existence of columns required. But when the script runs at the next time, it will hit error that says the columns was not found from the old table in the "update" query. Because the columns were dropped when the script run at the first time.
Is there other ways to solve?
you will not be able to update using join, But you can do like this :
Update NewB set NewB.columnA = (select OldA.columnA from OldA where NewB.ID = OldA.ID);
Update NewB set NewB.columnB = (select OldA.columnB from OldA where NewB.ID = OldA.ID);
I don't know which database you are using, in database there are some system tables, from where you can get whether the column does exist in table or not, like in oracle, All_TAB_COLUMNS contains the information of all the columns of tables, so you can hit that table like below :
select 1 from ALL_TAB_COLUMNS where TABLE_NAME='OldA' and COLUMN_NAME in ('columnA','columnB');
if resulting records are empty that means specified columns are not present in the table so you can skip your queries.
There must be something wrong with your is column exists check. I have similar DDL and DML operations many times. As you did not show how you are checking column existence I am not able to tell you what's wrong.
Anyway, you are adding a new column to a table. We can check if such column exists, if not - run the script, if yes- skip the script. And here is the check:
IF EXISTS(SELECT 1 FROM [sys].[columns] WHERE OBJECT_ID('[dbo].[NewB]') = [object_id] AND [name] = 'columnA')
BEGIN
BEGIN TRANSACTION;
....
COMMIT TRANSACTION;
END;
I am trying to add a column to a tsql table, i do this using SMO in c#. Altering the table is fine but i want to set the column to have a value. The table contains 650 million rows and the update query is taking over a day and a half to run.
Update [TempDatabase].[dbo].[table1] set RawSource = 'DTP'
This is the query I am running above.
Can anyone think of a more efficient way of doing this?
Thanks in advance.
Sometimes, it is more efficient to copy the table with the new value and re-create the table in a single command. Also, you might want to be sure that you have minimal logging for these operations.
Probably the best solution is to use a default value when you create the column:
alter table table1 add RawSource varchar(255) not null default 'DTP';
If you don't want the default moving forward, you can remove it after the column is added.
Another method uses computed columns, but basically does the same thing:
alter table table1 add _RawSource varchar(255);
alter table1 add RawSource as (coalesce(_RawSource, 'DTP'));
at the time of addition of column to table only we can set a default value which will applies for all rows
Note:U should keep not null compulsory because if not all rows are applicable with nulls
alter table table_name
add row_source nvarchar(5) not null default(N'DTP')
I have a "source data" table with columns A,B,C,D,E,F
I use this table to populate a live table by using
INSERT INTO LIVETABLE
SELECT *
FROM SOURCEDATATABLE
Recently, a new column (C1) was added to the LIVETABLE
All I want to do is insert a C1 column into my SOURCEDATATABLE between C and D so that it now is A,B,C,C1,D,E,F. There is no need to populate with data as the LIVETABLE accepts NULLs
Is there any easy solution?
EDIT - MISSING INFORMATION
This table is one of many and my approach to using the INSERT INTO is due to having to use dynamic SQL (for various other reasons) so I cannot specify the column names
There is a reason for the Mantra "I shall not use SELECT *" and you ran straight into it. Add the column to SOURCEDATATABLE (if necessary) and enumerate the columns in the SELECT clause using NULL for the new one.
The only way to insert a new column between two columns is to create a new table with the columns in the order you want, copy the data into it, drop the old table and rename the new table with the old name. Make sure you remove primary key identities to maintain the identity column.
I two tables, one table contains the names of columns, the other table contains the actual data that I need to display in a report. The data and columns are linked by a column key.
Is there a way to build a select statement that can use the column name from the column table for the actual temp table column?
Something like this;
Select A.value AS B.ColumnName
Simply put Can I create a table column name based on the value in another table in sql?
You can´t do it without using dynamic SQL as mentioned question that can be useful for you.
SQL Server: How to set column alias from another table during select?