How can I drop multiple tables in the same database that starts with same prefix?
Ex:
Query to delete 1 table
drop table project_id.db.test_table_<some_random_string>
But how can I drop all tables that start with the same prefix test_table_ in the same db?
A possible work around would be. (region is set eu)
BEGIN
DECLARE drop_statments ARRAY<string>;
DECLARE len int64 default 1;
SET drop_statments = (SELECT ARRAY_AGG( 'drop table ' || table_schema ||'.' || table_name)
FROM `region-eu.INFORMATION_SCHEMA.TABLES`
WHERE table_schema = 'db' and table_name like 'Table_Prefix%'
);
WHILE ARRAY_LENGTH(drop_statments) >= len DO
EXECUTE IMMEDIATE drop_statments[offset(len-1)];
SET len = len +1;
END WHILE ;
END;
You may use any of below INFORMATION_SCHEMA dataset.
-- Returns metadata for tables in a single dataset.
SELECT * FROM myDataset.INFORMATION_SCHEMA.TABLES;
-- Returns metadata for tables in a region.
SELECT * FROM region-us.INFORMATION_SCHEMA.TABLES;
Similar to narendra# solution, but using FOR..IN:
FOR drop_statement IN
(SELECT CONCAT("drop table ",table_schema,".", table_name, ";" ) AS value
FROM dataset.INFORMATION_SCHEMA.TABLES -- or region.INFORMATION_SCHEMA.TABLES
WHERE table_name LIKE "table_prefix%"
ORDER BY table_name DESC)
DO
EXECUTE IMMEDIATE(drop_statement.value); -- Here the table is dropped
END FOR;
It's also worth to mention, that you can change "table" to "view" also depending on the information returned from the INFORMATION_SCHEMA views.
Related
For Microsoft SQL Server I have following statement to only drop a column if the table exist.
IF EXISTS(SELECT 1
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = 'TEST_TABLE')
ALTER TABLE TEST_TABLE DROP COLUMN LEGACY_VALUE
GO
I was wondering if there was a related IF-EXISTS mechanism is present in Oracle.
All the metadata about the columns in Oracle Database is accessible using one of the following views.
user_tab_cols; -- For all tables owned by the user
all_tab_cols ; -- For all tables accessible to the user
dba_tab_cols; -- For all tables in the Database.
So, if you are looking for a column that exists and want to drop it, your code may look something like this ( see below).
Since this appears to be a one time task, is the effort really worth it?
DECLARE
v_column_exists number := 0;
BEGIN
Select count(*) into v_column_exists
from user_tab_cols
where upper(column_name) = 'LEGACY_VALUE''
and upper(table_name) = 'TEST_TABLE';
--and owner = 'SCOTT --*might be required if you are using all/dba views
if (v_column_exists = 1) then
execute immediate 'alter table test_table drop column legacy_value';
end if;
end;
/
I have a table called schema.exampletab, which has partitions where the partition name is on the form Pxxxxxx where the x's are partition periods (year and month YYYYMM) and then there is a local PK. I want to drop a partition, but I get the error message ORA-14006: Invalid partition name when attempting to drop it, but when I try to simply query data from a partition it selects and displays the data from the partition in question. Note that I am using a scheduler which uses date as a parameter using YYYYMMDD, so I usually substring.
For instance I can query data by using the following statement:
SELECT *
FROM schema.exampletab
PARTITION (P202110);
This returns 20 rows of data in my table.
I then try to drop the partition using the following statement:
ALTER TABLE schema.exampletab DROP PARTITION (concat(P,substr('20211011',1,6))
UPDATE INDEXES;
This however, leads to the ORA-14006 error message. In order to control that the partition exists I tried to look up that the schema, table, and partition exists in the all_tab_partitions where all partitions in the database I work on are logged.
select partition_name from all_tab_partitions
where table_owner = 'schema' and table_name = 'exampletab' and
substr(partition_name,2,7) = substr('20211022',1,6);
This returns the partition name P202110 in the query result.
I hoped I could use the drop partition with a subquery like this:
ALTER TABLE schema.exampletab DROP PARTITION select partition_name from all_tab_partitions
where table_owner = 'schema' and table_name = 'exampletab' and
substr(partition_name,2,7) = substr('20211022',1,6);
However, this still leads to ORA-14006 error. I have tried to write the partition name like 'P202110' and P202110 instead of the parenteces, but no luck.
How can I write the drop partition statement such that it drops the partition instead of giving the ORA-14006 error?
This is something which I have to do routinely and so it would be nice to know how to properly select and drop partitions, or truncate them, etc. Also, I use a scheduler which runs the sql queries at specified intervals so there I have to specify dates as a parameter, meaning that in my example code the YYYYMM is a parametervalue that gets parsed in and so I need to concactinate the P with this outputted parameter value, because if I type only P202110 it actually drops it.
You have two options, keeping in consideration that you are using sysdate to know which partition you should drop.
Option 1 -> Dynamic SQL and the result must be executed outside the query
select ' alter table '||table_owner||'.'||table_name||' drop partition '||partition_name||' update indexes ; '
from
dba_Tab_partitions
where table_owner = 'your_schema'
and table_name = 'your_table'
and partition_name = 'P'||substr(to_char(sysdate,'yyyymmdd'),1,6) ; ;
This query gives you the command output, but you need to execute it
alter table yourschema.yourtable drop partition P202110 update indexes;
Example in my own environment
SQL> select ' alter table '||table_owner||'.'||table_name||' drop partition '||partition_name||' update indexes ; '
from
dba_Tab_partitions
where table_owner = 'FDM_DATA'
and table_name = 'FDM_DIM_CUSTOMER'
and partition_name = 'P_'||substr(to_char(sysdate,'yyyymmdd'),1,6) ;
'ALTERTABLE'||TABLE_OWNER||'.'||TABLE_NAME||'DROPPARTITION'||PARTITION_NAME||'UP
--------------------------------------------------------------------------------
alter table FDM_DATA.FDM_DIM_CUSTOMER drop partition P_202110 update indexes ;
Option 2 -> PLSQL
A better option is to use PLSQL. A small example when you want to drop only one partition based on the current sysdate. You can extend / modify this code to cover any kind of time frame.
declare
v_owner varchar2(128) := 'YOUR_SCHEMA';
v_table_name varchar2(128) := 'YOUR_TABLE';
v_partition_name varchar2(128);
begin
select partition_name into v_partition_name from all_tab_partitions
where table_owner = v_owner and
table_name = v_table_name and
partition_name = 'P'||substr(to_char(sysdate,'yyyymmdd'),1,6) ;
execute immediate 'alter table '||v_owner||'.'||v_table_name||' drop partition '||v_partition_name||' update indexes' ;
exception
when no_data_found then null; -- if there is no partition, nothing to do and no error is raised
when others then raise;
end;
/
You cannot use "expressions" in partition name
This is wrong:
ALTER TABLE schema.exampletab DROP PARTITION (concat(P,substr('20211011',1,6))
UPDATE INDEXES;
this is correct:
ALTER TABLE schema.exampletab DROP PARTITION P20211011
UPDATE INDEXES;
You may use this code to drop partitions dynamically. Just update C_OWNER ,C_TABLE_NAME , C_PARTITION_TEMPLATE in the header. Please pay attention that the sql command is built dynamically, but when it is ready is has the partition name fully parsed.
declare
C_OWNER varchar2(128) := 'MYOWNER';
C_TABLE_NAME varchar2(128) := 'MYTABLE';
C_PARTITION_TEMPLATE varchar2(128) := '2011';
cursor part_cur is
select *
from all_tab_partitions
where table_owner=C_OWNER and
table_name = C_TABLE_NAME and
partition_name like '%'||C_PARTITION_TEMPLATE||'%'
order by partition_position;
BEGIN
for part_rec in part_cur loop
execute immediate 'ALTER TABLE "'||part_rec.table_owner||'"."'||part_rec.table_name||'"'||
' DROP PARTITION ("'||part_rec.partition_name||'") UPDATE INDEXES';
end loop;
END;
/
I need to get an id from a table, whose table name is defined by running another query.
I tried to implement it by defining a variable that saves the results from the first query. Then I created a second query that consumes the table name from the first one.
define tablename = (SELECT table_name FROM tables_names WHERE row_id = 147);
define rowid = SELECT row_id FROM &tablename WHERE title is NULL;
select * from &rowid;
However it doesn't work. I also tried to create a stored procedure, but I don't understand how it should work either:
DECLARE
tablename varchar(128);
rowid int;
BEGIN
SELECT table_name INTO tablename FROM tables_names WHERE row_id = 147);
SELECT row_id INTO rowid FROM &tablename WHERE title is NULL;
END;
The output should give me the expected rowid. I'm not an Oracle expert and this seems like a simple thing, but I don't know how to achieve it.
Use execute immediate as following:
DECLARE
rowid_ int; -- dont use oracle reserved words as variable name.
-- added _ after rowid
BEGIN
EXECUTE IMMEDIATE 'SELECT row_id FROM '
|| (SELECT table_name FROM tables_names WHERE row_id = 147)
|| ' WHERE title is NULL' INTO ROWID_;
-- do something with rowid_ or other logic
END;
/
Cheers!!
This is called dynamic sql.
Edit the procedure and have it do
EXECUTE IMMEDIATE
"SELECT row_id INTO :x FROM " || tablename || " WHERE title IS NULL"
USING rowid;
This is from memory so it might not work, but should give you a good start on how to do it
I have the following table name template, there are a couple with the same name and a number at the end: fmj.backup_semaforo_geo_THENUMBER, for example:
select * from fmj.backup_semaforo_geo_06391442
select * from fmj.backup_semaforo_geo_06398164
...
Lets say I need to select a column from every table which succeeds with the 'fmj.backup_semaforo_geo_%' filter, I tried this:
SELECT calle --This column is from the backup_semaforo_geo_# tables
FROM (SELECT table_name
FROM all_tables
WHERE owner = 'FMJ' AND table_name LIKE 'BACKUP_SEMAFORO_GEO_%');
But I'm getting the all_tables tables name data:
TABLE_NAME
----------
BACKUP_SEMAFORO_GEO_06391442
BACKUP_SEMAFORO_GEO_06398164
...
How can I achieve that without getting the all_tables output?
Thanks.
Presumably your current query is getting ORA-00904: "CALLE": invalid identifier, because the subquery doesn't have a column called CALLE. You can't provide a table name to a query at runtime like that, unfortunately, and have to resort to dynamic SQL.
Something like this will loop through all the tables and for each one will get all the values of CALLE from each one, which you can then loop through. I've used DBMS_OUTPUT to display them, assuming you're doing this in SQL*Plus or something that can deal with that; but you may want to do something else with them.
set serveroutput on
declare
-- declare a local collection type we can use for bulk collect; use any table
-- that has the column, or if there isn't a stable one use the actual data
-- type, varchar2(30) or whatever is appropriate
type t_values is table of table.calle%type;
-- declare an instance of that type
l_values t_values;
-- declare a cursor to generate the dynamic SQL; where this is done is a
-- matter of taste (can use 'open x for select ...', then fetch, etc.)
-- If you run the query on its own you'll see the individual selects from
-- all the tables
cursor c1 is
select table_name,
'select calle from ' || owner ||'.'|| table_name as query
from all_tables
where owner = 'FMJ'
and table_name like 'BACKUP_SEMAFORO_GEO%'
order by table_name;
begin
-- loop around all the dynamic queries from the cursor
for r1 in c1 loop
-- for each one, execute it as dynamic SQL, with a bulk collect into
-- the collection type created above
execute immediate r1.query bulk collect into l_values;
-- loop around all the elements in the collection, and print each one
for i in 1..l_values.count loop
dbms_output.put_line(r1.table_name ||': ' || l_values(i));
end loop;
end loop;
end;
/
May be a dynamic SQL in a PLSQL program;
for a in (SELECT table_name
FROM all_tables
WHERE owner = 'FMJ' AND table_name LIKE 'BACKUP_SEMAFORO_GEO_%')
LOOP
sql_stmt := ' SELECT calle FROM' || a.table_name;
EXECUTE IMMEDIATE sql_stmt;
...
...
END LOOP;
How do I add a simple check before adding a column to a table for an oracle db? I've included the SQL that I'm using to add the column.
ALTER TABLE db.tablename
ADD columnname NVARCHAR2(30);
All the metadata about the columns in Oracle Database is accessible using one of the following views.
user_tab_cols; -- For all tables owned by the user
all_tab_cols ; -- For all tables accessible to the user
dba_tab_cols; -- For all tables in the Database.
So, if you are looking for a column like ADD_TMS in SCOTT.EMP Table and add the column only if it does not exist, the PL/SQL Code would be along these lines..
DECLARE
v_column_exists number := 0;
BEGIN
Select count(*) into v_column_exists
from user_tab_cols
where upper(column_name) = 'ADD_TMS'
and upper(table_name) = 'EMP';
--and owner = 'SCOTT --*might be required if you are using all/dba views
if (v_column_exists = 0) then
execute immediate 'alter table emp add (ADD_TMS date)';
end if;
end;
/
If you are planning to run this as a script (not part of a procedure), the easiest way would be to include the alter command in the script and see the errors at the end of the script, assuming you have no Begin-End for the script..
If you have file1.sql
alter table t1 add col1 date;
alter table t1 add col2 date;
alter table t1 add col3 date;
And col2 is present,when the script is run, the other two columns would be added to the table and the log would show the error saying "col2" already exists, so you should be ok.
Or, you can ignore the error:
declare
column_exists exception;
pragma exception_init (column_exists , -01430);
begin
execute immediate 'ALTER TABLE db.tablename ADD columnname NVARCHAR2(30)';
exception when column_exists then null;
end;
/
Normally, I'd suggest trying the ANSI-92 standard meta tables for something like this but I see now that Oracle doesn't support it.
-- this works against most any other database
SELECT
*
FROM
INFORMATION_SCHEMA.COLUMNS C
INNER JOIN
INFORMATION_SCHEMA.TABLES T
ON T.TABLE_NAME = C.TABLE_NAME
WHERE
C.COLUMN_NAME = 'columnname'
AND T.TABLE_NAME = 'tablename'
Instead, it looks like you need to do something like
-- Oracle specific table/column query
SELECT
*
FROM
ALL_TAB_COLUMNS
WHERE
TABLE_NAME = 'tablename'
AND COLUMN_NAME = 'columnname'
I do apologize in that I don't have an Oracle instance to verify the above. If it does not work, please let me know and I will delete this post.
To check column exists
select column_name as found
from user_tab_cols
where table_name = '__TABLE_NAME__'
and column_name = '__COLUMN_NAME__'
Reference link