I am trying to find how many occurrences of a particular value there are in a particular column in an Oracle database. The column is used in dozens of tables and I'm going to have to run the queries many times, so I don't want to query each table individually. I can get a list of the tables to search with something like:
Select table_name from all_tab_cols
join all_tables using (table_name)
where column_name = 'EmployeeId' and num_rows > 0
The next step is to iterate through that list of table names and output each table that contains a particular value in the EmployeeId column. For example, output might be something like:
**Table Name Column_name # Rows for EmployeeId = '123456'**
Table 1 EmployeeId 1
Table 2 EmployeeId 12
etc.
I'm not a developer and don't have experience using cursors in SQL scripts, so any help would be greatly appreciated.
try using CURSOR FOR LOOP.
Probably it may look as shown below (not tried).
BEGIN
FOR item IN
(Select table_name,column_name,num_rows from all_tab_cols
join all_tables using (table_name)
where column_name = 'EmployeeId' and num_rows > 0)
LOOP
DBMS_OUTPUT.PUT_LINE
(item.table_name || ' ' || item.column_name ||' '||item.num_rows);
END LOOP;
END;
Related
I am trying to loop through 5 tables all with a similar naming format. I am able to return the tables names by using the query
select table_name from all tables
where table_name like '
order by table_name
My intention is to insert the data from all the 5 tables into one table where a particular date condition is met. I know I can do this via union all but this makes my script very long as I have to paste the same script for 5 tables, I was wondering if there is a way to do without using union all but rather using dynamic sql? I am new to dynamic sql.
It might look like this:
begin
for cur_r in (select table_name
from all_tables
where table_name like 'ABC%'
)
loop
execute immediate
'insert into target_table (id, name, address) ' ||
'select id, name, address from ' || cur_r.table_name ||
' where date_column = ' || trunc(sysdate);
end loop;
end;
/
loop through all_tables, fetching only those you're interested in
compose insert statement, presuming that all tables (from previous step) share the same set of common columns
include where clause, if you want
I am trying to derive a table with counts from multiple tables. The tables are not on my schema. The table names on the schema that I am interested in all start with 'STAF_' and end with '_TS'. The criteria i am looking for is where SEP = 'MO'. So for example, the query in its base form is:
select area, count(SEP) areacount
from mous.STAF_0001_TS
where SEP = 'MO'
group by area;
I have about 1000 tables that i'd like to do this for.
Ultimatly, I'd like the output to be a table on my schema that looks like the following:
area| areacount
0001| 3
0002| 7
0003| 438
Thank you.
As a first step I'd write an SQL query that generates an SQL query:
SELECT 'SELECT area, count(*) FROM '||c.table_name||'UNION ALL' as run_me
FROM all_tables c
WHERE c.table_name LIKE 'STAF\_%\_MS' escape '\'
Running this will produce an output that is another SQL query. Copy the result text out of your results grid and paste it back into your query pane. Delete the final UNION ALL and run it
Once you dig how to write an SQL query that generate an SQL query, you can look at turning it into a view, or creating a dynamic query in a string.
Gotta say, this is a horrible way to store data; you'd be better off using ONE table with an extra column containing whatever is in xxx of STAF_xxx_MS right now
In Oracle 12c, you can embed a FUNCTION that will query the number of rows in any given table. Then you can use that function in your main query. Here is an example:
WITH FUNCTION cnt ( p_owner VARCHAR2, p_table_name VARCHAR2 ) RETURN NUMBER IS
l_cnt NUMBER;
BEGIN
EXECUTE IMMEDIATE 'SELECT count(*) INTO :cnt FROM ' || p_owner || '.' || p_table_name INTO l_cnt;
RETURN l_cnt;
EXCEPTION WHEN OTHERS THEN
RETURN NULL; -- This will happen for entries in ALL_TABLES that are not directly accessible (e.g., IOT overflow tables)
END cnt;
SELECT t.owner, t.table_name, cnt(t.owner, t.table_name)
FROM all_tables t
where t.table_Name like 'STAF\_%\_MS' escape '\';
I have a table as shown below. This table will be generated dynamically and I have no prior idea about what value it is going to hold.
------------------------------------------
TABLE_NAME COLUMN_NAME CHAR_LENGTH
------------------------------------------
EMPLOYEE COL1 100
EMPLOYEE COL2 200
EMPLOYEE COL3 300
EMPLOYEE COL4 400
Based on this table, I want to build a query in such a way that it would give me those columns, that contains data having char length greater than CHAR_LENGTH column value.
For example if COL2 contains data having char length 500 (>200), then query would give me COL2.
I don't have any draft code to show my attempt, as I have no idea how would I do this.
I don't think this is possible in pure SQL due to the dynamic nature of your requirement. You'll need some form of PL/SQL.
Assuming you're ok with simply outputting the desired results, here is a PL/SQL block that will get the job done:
declare
wExists number(1);
begin
for rec in (select * from your_dynamic_table)
loop
execute immediate 'select count(*)
from dual
where exists (select null
from ' || rec.table_name || ' t
where length(t.' || rec.column_name || ') > ' || rec.char_length || ')'
into wExists;
if wExists = 1 then
dbms_output.put_line(rec.column_name);
end if;
end loop;
end;
You'll also notice the use of the exists clause to optimize the query, so as not to iterate over the whole table unnecessarily, when possible.
Alternatively, if you want the results to be queryable, you can consider converting the code to a pipelined function.
select column_name
from (
select statement that builds the table output
) A
where char_length<length(column_name)
will that help?
You would need a procedure to achieve the same :
Here I am treating the all_tab_columns table in Oracle, which is a default table with much similar structure as your reference example.(Try select * from all_tab_columns). The structure of all_tab_columns is much like yours, except that you will never find a varchar record whose value has exceeded its data length(obvious database level constraint). Date fields may exceed data length, and do reflect in this procedure's output. I am searching all columns in EMPLOYEES whose size exceeds what is specified.
DECLARE
cursor c is select column_name,data_length,table_name from all_tab_columns where table_name=:Table_name;
V_INDEX_NAME all_tab_columns.column_name%type;
v_data_length all_tab_columns.data_length%type;
V_NUMBER PLS_INTEGER;
v_table_name all_tab_columns.table_name%type;
BEGIN
open c;
LOOP
FETCH c into v_index_name,v_data_length,v_table_name;
EXIT when c%NOTFOUND;
v_number :=0;
execute immediate 'select count(*) from '|| :Table_name ||' where length('||v_index_name||')>'||v_data_length into v_number;
if v_number>1 then
dbms_output.put_line(v_index_name||' has values greater than specified'||' '||V_INDEX_NAME||' '||v_data_length);
end if;
END LOOP;
close c;
END;
/
Replace all_tab_columns and its respective columns with the column name of your table.
DEFECTS : The table name is hardcoded. Trying to make the code generic execute immediate or any other trick. Will achieve soon.
EDIT : Defect fixed.
I have a problem in that I want my output to be a single table (lets call it Output) with 2 columns: one for the "TableName" and one for the DateTime of the last update (using the scn_to_timestamp(max(ora_rowscn)) command).
I have 100 tables and I want to pull in the last update date/times for all these tables into the Output table.
So I can do this:
insert into Output(TableName)
select table_name
from all_tables;
which will put all the tables I have from my database into the TableName column. But I don't know how to loop through each entry and use the tablename as a variable and pass this into the scn_to_timestamp(ora_rowscn).
I thought I would try something like below:
for counter in Output(TableName) LOOP
insert into Output(UpdateDate)
select scn_to_timestamp(max(ora_rowscn))
from counter;
END LOOP;
Any suggestions?
Thank you
This query is a little bit clumsy as it uses xmlgen to execute dynamic sql in a query, but it might work for you.
select x.*
from all_tables t,
xmltable('/ROWSET/ROW' passing
dbms_xmlgen.getxmltype('select ''' || t.table_name ||
''' tab_name, max(ora_rowscn) as la from ' ||
t.table_name)
COLUMNS tab_name varchar2(30) PATH 'TAB_NAME',
max_scn number PATH 'LA') x
Here is a sqlfiddle demo
You can also use PLSQL and then use execute immediate
Hi everyone what I'm wondering if I can do is create a table that lists the record counts of other tables. It would get those table names from a table. So let's assume I have the table TABLE_LIST that looks like this
name
---------
sports_products <-- contains 10 records
house_products <-- contains 8 records
beauty_products <-- contains 15 records
I would like to write a statement that pulls the names from those tables to query them and coount the records and ultimately produce this table
name numRecords
------------------------------
sports_products 10
house_products 8
beauty_products 15
So I think I would need to do something like this pseudo code
select *
from foreach tableName in select name from table_list
select count(*) as numRecords
from tableName
loop
You can have a function that is doing this for you via dynamic sql.
However, make sure to declare it as authid current_user. You do not want anyone to gain some sort of privilege elevation by exploiting your function.
create or replace function SampleFunction
(
owner in VarChar
,tableName in VarChar
) return integer authid current_user is
result Integer;
begin
execute immediate 'select count(*) from "' || owner || '"."' || tableName || '"'
INTO result;
return result;
end;
One option is to simply keep your DB statistics updated, use dbms_stats package or EM, and then
select num_rows
from all_tables
where table_name in (select name from table_list);
I think Robert Giesecke solution will work fine.
A more exotic way of solving this is by using dbms_xmlgen.getxml.
See for example: Identify a table with maximum rows in Oracle