I was wondering how can I drop table with concat by selecting value from other table.
This is what I am trying to figure out:
DROP TABLE SELECT 'table' || (select value from IncrementTable)
So basically table name is table6 for example.
Goal is: eg.. DROP TABLE table6
You can't do this directly. Table and column names have to be known when the statement is byte-compiled; they can't be generated at runtime. You have to figure out the table name and generate the appropriate statement string in the program using the database, and execute it.
Related
I found the similar question and solution for the SQL server. I want to replace all my null values with zero or empty strings. I can not use the update statement because my table has 255 columns and using the update for all columns will consume lots of time.
Can anyone suggest to me, how to update all the null values from all columns at once in PostgreSQL?
If you want to replace the data on the fly while selecting the rows you need:
SELECT COALESCE(maybe_null_column, 0)
If you want the change to be saved on the table you need to use an UPDATE. If you have a lot of rows you can use a tool like pg-batch
You can also create a new table and then swap the old one and the new one:
# Create new table with updated values
CREATE TABLE new_table AS
SELECT COALESCE(maybe_null_column, 0), COALESCE(maybe_null_column2, '')
FROM my_table;
# Swap table
ALTER TABLE my_table RENAME TO obsolete_table;
ALTER TABLE new_table RENAME TO my_table;
First: I'm working on a existing code and want to add some new stuff to it and I'm really new to ABAP
My goal: I want to duplicate an existing table and remove all values that occur multiple times. That - at least I think - works. Afterwards I want to INNER JOIN this new created table with another already existing table, but unfortunately I always get the following error:
Method MethodName "newCreatedTable" is not defined in the ABAP Dictionary as a table, projection view, or database view
Additional Info: As you can see I'm working inside of a method!
Here is my code what I've done so far:
creating new table and delete all duplicates
DATA newCreatedTable TYPE STANDARD TABLE OF existingTable.
SELECT columnName
FROM existingTable INTO TABLE newCreatedTable.
DELETE ADJACENT DUPLICATES
FROM newCreatedTable COMPARING columnName.
here is where the error happens
SELECT *
FROM anotherExistingTable as p
INNER JOIN newCreatedTable as t on t~columnName = p~columnName
...
I hope someone can help me out in this case! Thank You in advance!
If I'm not wrong your code looks like this:
DATA newCreatedTable TYPE STANDARD TABLE OF existingTable.
SELECT columnName FROM existingTable INTO TABLE newCreatedTable.
DELETE ADJACENT DUPLICATES
FROM newCreatedTable COMPARING columnName.
SELECT *
FROM anotherExistingTable
INNER JOIN newCreatedTable as t on t~columnName = p~columnName
If this is the case then you cannot make a SELECT on an internal table. You can only make this operation on a table that exists in the ABAP dictionary.
Your code should look like this:
DATA newCreatedTable TYPE STANDARD TABLE OF existingTable.
SELECT columnName
FROM existingTable INTO TABLE #newCreatedTable.
DELETE ADJACENT DUPLICATES FROM newCreatedTable COMPARING columnName.
SELECT *
FROM anotherExistingTable
FOR ALL ENTRIES IN #newCreatedTable " <-------------- Use FOR ALL ENTRIES
WHERE columnName = #newCreatedTable-columnName. " <-- in your code
select name into viewtable from stdinfo5
My error is:
There is already an object named 'viewtable' in the database.
Can someone explain: I want column with data (adding) into viewtable from the stdinfo5 table.
Thanks!
select ... into SomeTarget from SomeSource will create a physical table with the name SomeTarget!
You can use DROP TABLE SomeTarget to delete this table (carefull with real data!!!) or, what might be better, use select ... into #SomeTarget ....
The # before the name will create this table as temp table which is deleted automatically when it gets out of scope.
In your case it seems, that you do not want to delete the table, but you just want to add one more column. In this case you'd need something like ALTER TABLE viewtable ADD TheColumnName TheColumnType; and then use an UPDATE statement to fill this column. If possible, it was easier to delete the table and re-create it with the missing column...
How can I change DATA TYPE of a column from number to varchar2 without deleting the table data?
You can't.
You can, however, create a new column with the new data type, migrate the data, drop the old column, and rename the new column. Something like
ALTER TABLE table_name
ADD( new_column_name varchar2(10) );
UPDATE table_name
SET new_column_name = to_char(old_column_name, <<some format>>);
ALTER TABLE table_name
DROP COLUMN old_column_name;
ALTER TABLE table_name
RENAME COLUMN new_column_name TO old_coulumn_name;
If you have code that depends on the position of the column in the table (which you really shouldn't have), you could rename the table and create a view on the table with the original name of the table that exposes the columns in the order your code expects until you can fix that buggy code.
You have to first deal with the existing rows before you modify the column DATA TYPE.
You could do the following steps:
Add the new column with a new name.
Update the new column from old column.
Drop the old column.
Rename the new column with the old column name.
For example,
alter table t add (col_new varchar2(50));
update t set col_new = to_char(col_old);
alter table t drop column col_old cascade constraints;
alter table t rename column col_new to col_old;
Make sure you re-create any required indexes which you had.
You could also try the CTAS approach, i.e. create table as select. But, the above is safe and preferrable.
The most efficient way is probably to do a CREATE TABLE ... AS SELECT
(CTAS)
alter table table_name modify (column_name VARCHAR2(255));
Since we can't change data type of a column with values, the approach that I was followed as below,
Say the column name you want to change type is 'A' and this can be achieved with SQL developer.
First sort table data by other column (ex: datetime).
Next copy the values of column 'A' and paste to excel file.
Delete values of the column 'A' an commit.
Change the data type and commit.
Again sort table data by previously used column (ex: datetime).
Then paste copied data from excel and commit.
I have a table with names of other tables. How can I create a query that gets the table from the values?
For example, if my table has the values:
tables
------
users
users2
users3
I want to create Dynamic SQL function that knows how to take the values (i.e. the table names) from the reference table and then select * from that named value.
If you just want a one time script you can run the query:
select 'select * from ' || table_name || ';' cmd
from user_tables;
And then run the output