I have 2 database connections: a and b where they both share the same schema but not necessarily the same data. I need to check both database's total number of rows for each table using a loop and compare their counts.
Using a nested table collection, my attempt so far:
DECLARE
TYPE nt_rows IS TABLE OF NUMBER;
nt_rows1 nt_num := nt_num();
nt_rows2 nt_num := nt_num();
counter INT := 0;
CURSOR c_tables1 IS
SELECT TABLE_NAME
FROM ALL_TABLES
WHERE OWNER IN ('a')
ORDER BY TABLE_NAME ASC;
CURSOR c_tables2 IS
SELECT TABLE_NAME
FROM ALL_TABLES
WHERE OWNER IN ('b')
ORDER BY TABLE_NAME ASC;
BEGIN block: loop through each cursor and add them to each array
BEGIN
FOR i IN c_tables1 LOOP
nt_rows1.extend;
SELECT COUNT(*) FROM a.i.TABLE_NAME INTO nt_rows1(counter);
END LOOP;
The last line does not work where 'a' is the database connection name and i is index of each table_name.
I also tried:
nt_rows1(counter) := SELECT COUNT(*) FROM a.i.TABLE_NAME;
and it also doesn't work, any suggestions are appreciated.
If you want to query data from a table whose name is in a string (for example a local variable or a cursor field) and hence not known at compile time, you will need to use dynamic SQL.
Try replacing the line
SELECT COUNT(*) FROM a.i.TABLE_NAME INTO nt_rows1(counter);
with
EXECUTE IMMEDIATE 'SELECT COUNT(*) FROM a.' || i.TABLE_NAME INTO nt_rows1(counter);
Note also that your code is not incrementing the counter variable. Since you are starting with counter set to 0, and 0 isn't a valid index into a nested table, I would recommend adding a line to increment counter before the line above.
Related
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'm writing a pl/sql function. I need to select multiple rows from select statement:
SELECT pel.ceid
FROM pa_exception_list pel
WHERE trunc(pel.creation_date) >= trunc(SYSDATE-7)
if i use:
SELECT pel.ceid
INTO v_ceid
it only stores one value, but i need to store all values that this select returns. Given that this is a function i can't just use simple select because i get error, "INTO - is expected."
You can use a record type to do that. The below example should work for you
DECLARE
TYPE v_array_type IS VARRAY (10) OF NUMBER;
var v_array_type;
BEGIN
SELECT x
BULK COLLECT INTO
var
FROM (
SELECT 1 x
FROM dual
UNION
SELECT 2 x
FROM dual
UNION
SELECT 3 x
FROM dual
);
FOR I IN 1..3 LOOP
dbms_output.put_line(var(I));
END LOOP;
END;
So in your case, it would be something like
select pel.ceid
BULK COLLECT INTO <variable which you create>
from pa_exception_list
where trunc(pel.creation_Date) >= trunc(sysdate-7);
If you really need to store multiple rows, check BULK COLLECT INTO statement and examples. But maybe FOR cursor LOOP and row-by-row processing would be better decision.
You may store all in a rowtype parameter and show whichever column you want to show( assuming ceid is your primary key column, col1 & 2 are some other columns of your table ) :
SQL> set serveroutput on;
SQL> declare
l_exp pa_exception_list%rowtype;
begin
for c in ( select *
from pa_exception_list pel
where trunc(pel.creation_date) >= trunc(SYSDATE-7)
) -- to select multiple rows
loop
select *
into l_exp
from pa_exception_list
where ceid = c.ceid; -- to render only one row( ceid is primary key )
dbms_output.put_line(l_exp.ceid||' - '||l_exp.col1||' - '||l_exp.col2); -- to show the results
end loop;
end;
/
SET SERVEROUTPUT ON
BEGIN
FOR rec IN (
--an implicit cursor is created here
SELECT pel.ceid AS ceid
FROM pa_exception_list pel
WHERE trunc(pel.creation_date) >= trunc(SYSDATE-7)
)
LOOP
dbms_output.put_line(rec.ceid);
END LOOP;
END;
/
Notes from here:
In this case, the cursor FOR LOOP declares, opens, fetches from, and
closes an implicit cursor. However, the implicit cursor is internal;
therefore, you cannot reference it.
Note that Oracle Database automatically optimizes a cursor FOR LOOP to
work similarly to a BULK COLLECT query. Although your code looks as if
it fetched one row at a time, Oracle Database fetches multiple rows at
a time and allows you to process each row individually.
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.
Goal: Use a given subquery's results (a single column with many rows of names) to act as the outer select's selection field.
Currently, my subquery is the following:
SELECT column_name
FROM information_schema.columns
WHERE table_name = 'test_table' AND column_name not in ('colRemove');
What I am doing in this subquery is grabbing all the column names from a table (i.e. test_table) and outputting all except for the column name specified (i.e. colRemove). As stated in the "goal", I want to use this subquery as such:
SELECT (*enter subquery from above here*)
FROM actual_table
WHERE (*enter specific conditions*)
I am working on a Netezza SQL server that is version 7.0.4.4. Ideally, I would like to make the entire query executable in one line, but for now, a working solution would be much appreciated. Thanks!
Note: I do not believe that the SQL extensions has been installed (i.e. arrays), but I will need to double check this.
A year too late, here's the best I can come up with but, as you already noticed, it requires a stored procedure to do the dynamic SQL. The stored proc creates a view with the all the columns from the source table minus the one you want to exclude.
-- Create test data.
CREATE TABLE test (firstcol INTEGER, secondcol INTEGER, thirdcol INTEGER);
INSERT INTO test (firstcol, secondcol, thirdcol) VALUES (1, 2, 3);
INSERT INTO test (firstcol, secondcol, thirdcol) VALUES (4, 5, 6);
-- Install stored procedure.
CREATE OR REPLACE PROCEDURE CreateLimitedView (varchar(ANY), varchar(ANY)) RETURNS BOOLEAN
LANGUAGE NZPLSQL AS
BEGIN_PROC
DECLARE
tableName ALIAS FOR $1;
columnToExclude ALIAS FOR $2;
colRec RECORD;
cols VARCHAR(2000); -- Adjust as needed.
isfirstcol BOOLEAN;
BEGIN
isfirstcol := true;
FOR colRec IN EXECUTE
'SELECT ATTNAME AS NAME FROM _V_RELATION_COLUMN
WHERE
NAME=UPPER('||quote_literal(tableName)||')
AND ATTNAME <> UPPER('||quote_literal(columnToExclude)||')
ORDER BY ATTNUM'
LOOP
IF isfirstcol THEN
cols := colRec.NAME;
ELSE
cols := cols || ', ' || colRec.NAME;
END IF;
isfirstcol := false;
END LOOP;
-- Should really check if 'LimitedView' already exists as a view, table or synonym.
EXECUTE IMMEDIATE 'CREATE OR REPLACE VIEW LimitedView AS SELECT ' || cols || ' FROM ' || quote_ident(tableName);
RETURN true;
END;
END_PROC
;
-- Run the stored proc to create the view.
CALL CreateLimitedView('test', 'secondcol');
-- Select results from the view.
SELECT * FROM limitedView WHERE firstcol = 4;
FIRSTCOL | THIRDCOL
----------+----------
4 | 6
You could have the stored proc return a resultset directly but then you wouldn't be able to filter results with a WHERE clause.
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;