ORA-01422 :fetch returns more than requested number of rows
In my previous articles, I have given the proper idea of different oracle errors, which are frequently come. In this article, I will try to explain another common error, which has been searched on google approximately 10 k times per month. ORA-01422 is another simple error, which is commonly come in database when select into statement when it retrieves more than one row. All oracle errors are categorized in to two types one is network and memory issues and other are syntax errors come due to bad syntax. ORA-01422 is user-initiated mistake resulting from either a typo or a misunderstanding of how Oracle functions may work.
Cause and resolution of this error:
The ORA-01422 error is most common error, which will come because of the multiple reasons .The main reason of this error, is ‘SELECT INTO’ statement. Oracle has one important inbuilt error named ‘TOO_MANY_ROWS’ error.
1.More than requested rows in “Select into”:
If ‘Select Into’ statement returns more than one rows in variable then this error will come. The error says fetch returns more than requested number of rows means ‘Exact Fetch’ will return ‘More than one row’. The basic problem will come from ‘Select Into’ statement from oracle, which will return more than one rows. The select statement will fetch the record from multiple databases and multiple tables and it will store into variable. The Oracle engine will fetch more than one record for single specified row. The ORA-01422 error will trigger when PLSQL engine returns multiple rows of data. The select into statement has default setting, which is designed to retrieve one row, but when it retrieves more than one rows, the ORA-01422 error will trigger.
Consider following real life example:
If table named ‘test_error’ has more than one records and user tries to fetch all records in to one variable this error will come.
Procedure :
DECLARE
v_test VARCHAR2(30);
BEGIN
SELECT roll_no INTO v_test FROM test_error; —-Error statement
end;
Output:
Error report:
ORA-01422: exact fetch returns more than requested number of rows
ORA-06512: at line 4
01422. 00000 – “exact fetch returns more than requested number of rows”
*Cause: The number specified in exact fetch is less than the rows returned.
*Action: Rewrite the query or change number of rows requested
Resolution of this error:
Handle the exception:
Just make the small change in the specified code and write the exception block for the same.
Procedure :
DECLARE
V_SRNUM VARCHAR2(20);
DECLARE
v_test VARCHAR2(30);
BEGIN
SELECT roll_no INTO v_test FROM test_error;
exception WHEN too_many_rows THEN
dbms_output.put_line(‘Errors fetching are more than one’);
end;
The above procedure will handle the error and anonyms block will complete successfully.So if this kind of error will occure handle user defined exception named ‘TOO_MANY_ROWS’.
2. Add cursor with loop:
There are many primitive adjustments to resolve this error. The approach needs to be chosen by the user dependent on the database tables and scenarios. The error will occur because of multiple rows are returning so user will change the code by adding the cursor.
Therefore, the above procedure will be:
Declare
v_test VARCHAR2(30);
begin
for c in (SELECT roll_no INTO v_test FROM test_error)
loop
v_test := c.roll_no;
end loop;
end;
3. Recommend to use aggregate function:
This error will come because of multiple rows selection. Therefore, as per requirement if user uses the aggregate function like sum, count then it will fetch only one row.
Therefore, the above procedure will be:
DECLARE
v_test VARCHAR2(30);
BEGIN
SELECT count(roll_no) INTO v_test FROM test_error; —-Error statement
end;
4. Use of bulk collect:
This will pull more rows and variables but in a concise manner. However, be wary of using BULK COLLECT excessively as it can use a great deal of memory.
So there are different ways to deal with this error, my best recommendation is to use the cursor for fetching more than one rows and processing it.