Oracle SQL query that shows Oracle users connected and the sessions number for user
SELECT username Usuario_Oracle, COUNT (username) Numero_Sesiones
FROM v$session
GROUP BY username
ORDER BY Numero_Sesiones DESC;
Get number of objects per owner
SELECT owner, COUNT (owner) number_of_objects
FROM dba_objects
GROUP BY owner
ORDER BY number_of_objects DESC;
Convert number to words
More info: Converting number into words in Oracle
SELECT TO_CHAR (TO_DATE (1526, 'j'), 'jsp') FROM DUAL;
Output:
one thousand five hundred twenty-six
Find string in package source code
Below query will search for string ‘FOO_SOMETHING’ in all package source. This query comes handy when you want to find a particular procedure or function call from all the source code.
--search a string foo_something in package source code
SELECT *
FROM dba_source
WHERE UPPER (text) LIKE '%FOO_SOMETHING%'
AND owner = 'USER_NAME';
Convert Comma Separated Values into Table
The query can come quite handy when you have comma separated data string that you need to convert into table so that you can use other SQL queries like IN or NOT IN. Here we are converting ‘AA,BB,CC,DD,EE,FF’ string to table containing AA, BB, CC etc. as each row. Once you have this table you can join it with other table to quickly do some useful stuffs.
WITH csv
AS (SELECT 'AA,BB,CC,DD,EE,FF'
AS csvdata
FROM DUAL)
SELECT REGEXP_SUBSTR (csv.csvdata, '[^,]+', 1, LEVEL) pivot_char
FROM DUAL, csv
CONNECT BY REGEXP_SUBSTR (csv.csvdata,'[^,]+', 1, LEVEL) IS NOT NULL;
Find the last record from a table
This ones straight forward. Use this when your table does not have primary key or you cannot be sure if record having max primary key is the latest one.
SELECT *
FROM employees
WHERE ROWID IN (SELECT MAX (ROWID) FROM employees);
(OR)
SELECT * FROM employees
MINUS
SELECT *
FROM employees
WHERE ROWNUM < (SELECT COUNT (*) FROM employees);
Row Data Multiplication in Oracle
This query use some tricky math functions to multiply values from each row. Read below article for more details.
More info: Row Data Multiplication In Oracle
WITH tbl
AS (SELECT -2 num FROM DUAL
UNION
SELECT -3 num FROM DUAL
UNION
SELECT -4 num FROM DUAL),
sign_val
AS (SELECT CASE MOD (COUNT (*), 2) WHEN 0 THEN 1 ELSE -1 END val
FROM tbl
WHERE num < 0)
SELECT EXP (SUM (LN (ABS (num)))) * val
FROM tbl, sign_val
GROUP BY val;
Generating Random Data In Oracle
You might want to generate some random data to quickly insert in table for testing. Below query help you do that. Read this article for more details.
More info: Random Data in Oracle
SELECT LEVEL empl_id,
MOD (ROWNUM, 50000) dept_id,
TRUNC (DBMS_RANDOM.VALUE (1000, 500000), 2) salary,
DECODE (ROUND (DBMS_RANDOM.VALUE (1, 2)), 1, 'M', 2, 'F') gender,
TO_DATE (
ROUND (DBMS_RANDOM.VALUE (1, 28))
|| '-'
|| ROUND (DBMS_RANDOM.VALUE (1, 12))
|| '-'
|| ROUND (DBMS_RANDOM.VALUE (1900, 2010)),
'DD-MM-YYYY')
dob,
DBMS_RANDOM.STRING ('x', DBMS_RANDOM.VALUE (20, 50)) address
FROM DUAL
CONNECT BY LEVEL < 10000;
Random number generator in Oracle
Plain old random number generator in Oracle. This ones generate a random number between 0 and 100. Change the multiplier to number that you want to set limit for.
--generate random number between 0 and 100
SELECT ROUND (DBMS_RANDOM.VALUE () * 100) + 1 AS random_num FROM DUAL;
Check if table contains any data
This one can be written in multiple ways. You can create count(*) on a table to know number of rows. But this query is more efficient given the fact that we are only interested in knowing if table has any data.
SELECT 1
FROM TABLE_NAME
WHERE ROWNUM = 1;
Oracle Select Query
Oracle select query is used to fetch records from database. For example:
SELECT * from customers;
Oracle Insert Query
Oracle insert query is used to insert records into table. For example:
insert into customers values(101,'rahul','delhi');
Oracle Update Query
Oracle update query is used to update records of a table. For example:
update customers set name='bob', city='london' where id=101;
Oracle Delete Query
Oracle update query is used to delete records of a table from database. For example:
delete from customers where id=101;
Get position of 'o' in name 'John' from employee table
Select instr(FIRST_NAME,'o') from employee where first_name = 'John'
Oracle Truncate Query
Oracle update query is used to truncate or remove records of a table. It doesn't remove structure. For example:
truncate table customers;
Get First_Name from employee table after replacing 'o' with '$'
select REPLACE(FIRST_NAME,'o','$') from employee
Oracle Drop Query
Oracle drop query is used to drop a table or view. It doesn't have structure and data. For example:
drop table customers;
Write a query to find the total sales of each product.?
Solution:
This is a simple query. You just need to group by the data on PRODUCT_NAME and then find the sum of sales.
SELECT P.PRODUCT_NAME,
NVL( SUM( S.QUANTITY*S.PRICE ), 0) TOTAL_SALES
FROM PRODUCTS P
LEFT OUTER JOIN
SALES S
ON (P.PRODUCT_ID = S.PRODUCT_ID)
GROUP BY P.PRODUCT_NAME;
Write a query to find the products whose quantity sold in a year should be greater than the average quantity of the product sold across all the years?
Solution:
This can be solved with the help of correlated query. The SQL query for this is
SELECT P.PRODUCT_NAME,
S.YEAR,
S.QUANTITY
FROM PRODUCTS P,
SALES S
WHERE P.PRODUCT_ID = S.PRODUCT_ID
AND S.QUANTITY >
(SELECT AVG(QUANTITY)
FROM SALES S1
WHERE S1.PRODUCT_ID = S.PRODUCT_ID
);
Write a query to compare the products sales of "IPhone" and "Samsung" in each year? The output should look like as
YEAR IPHONE_QUANT SAM_QUANT IPHONE_PRICE SAM_PRICE
---------------------------------------------------
2010 10 20 9000 7000
2011 15 18 9000 7000
2012 20 20 9000 7000
Solution:
By using self-join SQL query we can get the required result. The required SQL query is
SELECT S_I.YEAR,
S_I.QUANTITY IPHONE_QUANT,
S_S.QUANTITY SAM_QUANT,
S_I.PRICE IPHONE_PRICE,
S_S.PRICE SAM_PRICE
FROM PRODUCTS P_I,
SALES S_I,
PRODUCTS P_S,
SALES S_S
WHERE P_I.PRODUCT_ID = S_I.PRODUCT_ID
AND P_S.PRODUCT_ID = S_S.PRODUCT_ID
AND P_I.PRODUCT_NAME = 'IPhone'
AND P_S.PRODUCT_NAME = 'Samsung'
AND S_I.YEAR = S_S.YEAR
Write a query to find the ratios of the sales of a product?
Solution:
The ratio of a product is calculated as the total sales price in a particular year divide by the total sales price across all years. Oracle provides RATIO_TO_REPORT analytical function for finding the ratios. The SQL query is
SELECT P.PRODUCT_NAME,
S.YEAR,
RATIO_TO_REPORT(S.QUANTITY*S.PRICE)
OVER(PARTITION BY P.PRODUCT_NAME ) SALES_RATIO
FROM PRODUCTS P,
SALES S
WHERE (P.PRODUCT_ID = S.PRODUCT_ID);
In the SALES table quantity of each product is stored in rows for every year. Now write a query to transpose the quantity for each product and display it in columns? The output should look like as
PRODUCT_NAME QUAN_2010 QUAN_2011 QUAN_2012
------------------------------------------
IPhone 10 15 20
Samsung 20 18 20
Nokia 25 16 8
Solution:
Oracle 11g provides a pivot function to transpose the row data into column data. The SQL query for this is
SELECT * FROM
(
SELECT P.PRODUCT_NAME,
S.QUANTITY,
S.YEAR
FROM PRODUCTS P,
SALES S
WHERE (P.PRODUCT_ID = S.PRODUCT_ID)
)A
PIVOT ( MAX(QUANTITY) AS QUAN FOR (YEAR) IN (2010,2011,2012));
If you are not running oracle 11g database, then use the below query for transposing the row data into column data.
SELECT P.PRODUCT_NAME,
MAX(DECODE(S.YEAR,2010, S.QUANTITY)) QUAN_2010,
MAX(DECODE(S.YEAR,2011, S.QUANTITY)) QUAN_2011,
MAX(DECODE(S.YEAR,2012, S.QUANTITY)) QUAN_2012
FROM PRODUCTS P,
SALES S
WHERE (P.PRODUCT_ID = S.PRODUCT_ID)
GROUP BY P.PRODUCT_NAME;
SELECT username Usuario_Oracle, COUNT (username) Numero_Sesiones
FROM v$session
GROUP BY username
ORDER BY Numero_Sesiones DESC;
Get number of objects per owner
SELECT owner, COUNT (owner) number_of_objects
FROM dba_objects
GROUP BY owner
ORDER BY number_of_objects DESC;
Convert number to words
More info: Converting number into words in Oracle
SELECT TO_CHAR (TO_DATE (1526, 'j'), 'jsp') FROM DUAL;
Output:
one thousand five hundred twenty-six
Find string in package source code
Below query will search for string ‘FOO_SOMETHING’ in all package source. This query comes handy when you want to find a particular procedure or function call from all the source code.
--search a string foo_something in package source code
SELECT *
FROM dba_source
WHERE UPPER (text) LIKE '%FOO_SOMETHING%'
AND owner = 'USER_NAME';
Convert Comma Separated Values into Table
The query can come quite handy when you have comma separated data string that you need to convert into table so that you can use other SQL queries like IN or NOT IN. Here we are converting ‘AA,BB,CC,DD,EE,FF’ string to table containing AA, BB, CC etc. as each row. Once you have this table you can join it with other table to quickly do some useful stuffs.
WITH csv
AS (SELECT 'AA,BB,CC,DD,EE,FF'
AS csvdata
FROM DUAL)
SELECT REGEXP_SUBSTR (csv.csvdata, '[^,]+', 1, LEVEL) pivot_char
FROM DUAL, csv
CONNECT BY REGEXP_SUBSTR (csv.csvdata,'[^,]+', 1, LEVEL) IS NOT NULL;
Find the last record from a table
This ones straight forward. Use this when your table does not have primary key or you cannot be sure if record having max primary key is the latest one.
SELECT *
FROM employees
WHERE ROWID IN (SELECT MAX (ROWID) FROM employees);
(OR)
SELECT * FROM employees
MINUS
SELECT *
FROM employees
WHERE ROWNUM < (SELECT COUNT (*) FROM employees);
 |
| Oracle SQL Queries Most Frequently Asked In Fiserv Written Test Interview |
Row Data Multiplication in Oracle
This query use some tricky math functions to multiply values from each row. Read below article for more details.
More info: Row Data Multiplication In Oracle
WITH tbl
AS (SELECT -2 num FROM DUAL
UNION
SELECT -3 num FROM DUAL
UNION
SELECT -4 num FROM DUAL),
sign_val
AS (SELECT CASE MOD (COUNT (*), 2) WHEN 0 THEN 1 ELSE -1 END val
FROM tbl
WHERE num < 0)
SELECT EXP (SUM (LN (ABS (num)))) * val
FROM tbl, sign_val
GROUP BY val;
Generating Random Data In Oracle
You might want to generate some random data to quickly insert in table for testing. Below query help you do that. Read this article for more details.
More info: Random Data in Oracle
SELECT LEVEL empl_id,
MOD (ROWNUM, 50000) dept_id,
TRUNC (DBMS_RANDOM.VALUE (1000, 500000), 2) salary,
DECODE (ROUND (DBMS_RANDOM.VALUE (1, 2)), 1, 'M', 2, 'F') gender,
TO_DATE (
ROUND (DBMS_RANDOM.VALUE (1, 28))
|| '-'
|| ROUND (DBMS_RANDOM.VALUE (1, 12))
|| '-'
|| ROUND (DBMS_RANDOM.VALUE (1900, 2010)),
'DD-MM-YYYY')
dob,
DBMS_RANDOM.STRING ('x', DBMS_RANDOM.VALUE (20, 50)) address
FROM DUAL
CONNECT BY LEVEL < 10000;
Random number generator in Oracle
Plain old random number generator in Oracle. This ones generate a random number between 0 and 100. Change the multiplier to number that you want to set limit for.
--generate random number between 0 and 100
SELECT ROUND (DBMS_RANDOM.VALUE () * 100) + 1 AS random_num FROM DUAL;
Check if table contains any data
This one can be written in multiple ways. You can create count(*) on a table to know number of rows. But this query is more efficient given the fact that we are only interested in knowing if table has any data.
SELECT 1
FROM TABLE_NAME
WHERE ROWNUM = 1;
Oracle Select Query
Oracle select query is used to fetch records from database. For example:
SELECT * from customers;
Oracle Insert Query
Oracle insert query is used to insert records into table. For example:
insert into customers values(101,'rahul','delhi');
Oracle Update Query
Oracle update query is used to update records of a table. For example:
update customers set name='bob', city='london' where id=101;
Oracle Delete Query
Oracle update query is used to delete records of a table from database. For example:
delete from customers where id=101;
Get position of 'o' in name 'John' from employee table
Select instr(FIRST_NAME,'o') from employee where first_name = 'John'
Oracle Truncate Query
Oracle update query is used to truncate or remove records of a table. It doesn't remove structure. For example:
truncate table customers;
Get First_Name from employee table after replacing 'o' with '$'
select REPLACE(FIRST_NAME,'o','$') from employee
Oracle Drop Query
Oracle drop query is used to drop a table or view. It doesn't have structure and data. For example:
drop table customers;
Write a query to find the total sales of each product.?
Solution:
This is a simple query. You just need to group by the data on PRODUCT_NAME and then find the sum of sales.
SELECT P.PRODUCT_NAME,
NVL( SUM( S.QUANTITY*S.PRICE ), 0) TOTAL_SALES
FROM PRODUCTS P
LEFT OUTER JOIN
SALES S
ON (P.PRODUCT_ID = S.PRODUCT_ID)
GROUP BY P.PRODUCT_NAME;
Write a query to find the products whose quantity sold in a year should be greater than the average quantity of the product sold across all the years?
Solution:
This can be solved with the help of correlated query. The SQL query for this is
SELECT P.PRODUCT_NAME,
S.YEAR,
S.QUANTITY
FROM PRODUCTS P,
SALES S
WHERE P.PRODUCT_ID = S.PRODUCT_ID
AND S.QUANTITY >
(SELECT AVG(QUANTITY)
FROM SALES S1
WHERE S1.PRODUCT_ID = S.PRODUCT_ID
);
Write a query to compare the products sales of "IPhone" and "Samsung" in each year? The output should look like as
YEAR IPHONE_QUANT SAM_QUANT IPHONE_PRICE SAM_PRICE
---------------------------------------------------
2010 10 20 9000 7000
2011 15 18 9000 7000
2012 20 20 9000 7000
Solution:
By using self-join SQL query we can get the required result. The required SQL query is
SELECT S_I.YEAR,
S_I.QUANTITY IPHONE_QUANT,
S_S.QUANTITY SAM_QUANT,
S_I.PRICE IPHONE_PRICE,
S_S.PRICE SAM_PRICE
FROM PRODUCTS P_I,
SALES S_I,
PRODUCTS P_S,
SALES S_S
WHERE P_I.PRODUCT_ID = S_I.PRODUCT_ID
AND P_S.PRODUCT_ID = S_S.PRODUCT_ID
AND P_I.PRODUCT_NAME = 'IPhone'
AND P_S.PRODUCT_NAME = 'Samsung'
AND S_I.YEAR = S_S.YEAR
Write a query to find the ratios of the sales of a product?
Solution:
The ratio of a product is calculated as the total sales price in a particular year divide by the total sales price across all years. Oracle provides RATIO_TO_REPORT analytical function for finding the ratios. The SQL query is
SELECT P.PRODUCT_NAME,
S.YEAR,
RATIO_TO_REPORT(S.QUANTITY*S.PRICE)
OVER(PARTITION BY P.PRODUCT_NAME ) SALES_RATIO
FROM PRODUCTS P,
SALES S
WHERE (P.PRODUCT_ID = S.PRODUCT_ID);
In the SALES table quantity of each product is stored in rows for every year. Now write a query to transpose the quantity for each product and display it in columns? The output should look like as
PRODUCT_NAME QUAN_2010 QUAN_2011 QUAN_2012
------------------------------------------
IPhone 10 15 20
Samsung 20 18 20
Nokia 25 16 8
Solution:
Oracle 11g provides a pivot function to transpose the row data into column data. The SQL query for this is
SELECT * FROM
(
SELECT P.PRODUCT_NAME,
S.QUANTITY,
S.YEAR
FROM PRODUCTS P,
SALES S
WHERE (P.PRODUCT_ID = S.PRODUCT_ID)
)A
PIVOT ( MAX(QUANTITY) AS QUAN FOR (YEAR) IN (2010,2011,2012));
If you are not running oracle 11g database, then use the below query for transposing the row data into column data.
SELECT P.PRODUCT_NAME,
MAX(DECODE(S.YEAR,2010, S.QUANTITY)) QUAN_2010,
MAX(DECODE(S.YEAR,2011, S.QUANTITY)) QUAN_2011,
MAX(DECODE(S.YEAR,2012, S.QUANTITY)) QUAN_2012
FROM PRODUCTS P,
SALES S
WHERE (P.PRODUCT_ID = S.PRODUCT_ID)
GROUP BY P.PRODUCT_NAME;
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