Advertisements
Advertisements
Question
Differentiate between count() and count(*) functions in SQL with appropriate examples.
Solution
COUNT(*) returns the count of all rows in the table, whereas COUNT() is used with Column_Name passed as an argument and counts the number of non-NULL values in a column that is given as an argument.
Example: Table: EMPL
| EMPNO | ENAME | JOB | SAL | DEPTNO |
| 8270 | JACK | SALESMAN | 2985 | 10 |
| 8566 | ALI | CLERK | 9870 | 20 |
| 8922 | AJAY | NULL | 8760 | 30 |
| 8736 | BINDU | CLERK | 5643 | 20 |
| 8822 | JOY | MANAGER | 3000 | 10 |
e.g. SELECT COUNT(*) FROM EMPL;
Output
| COUNT(*) |
| 5 |
e.g. SELECT COUNT(JOB) FROM EMPL;
Output
| COUNT(JOB) |
| 4 |
Since JOB has 1 NULL value.
APPEARS IN
RELATED QUESTIONS
______ is used to get a specified day of the month for a given date.
______ keyword is used to find out the number of values in a column?
The MAX () function finds the
What will be the output of the following SQL statement?
SELECT DAY NAME (2022-04-08)
Which command is used to delete a table? (in SQL)
Identify Single Row function of MySQL among the following.
What will be returned by the given query? select mid("Computer", 2, 4) = ______.
What will be returned by the given query? select substr("Computer", 4) = ______.
What will be returned by the given query? select power(3, 2) = ______.
What will be returned by the given query? Select length(trim("ABC Public School")) = ______.
What will be returned by the given query? SELECT MID('LeaminglsFun', 2, 4) = ______.
The ______ function returns m raised to the nth power.
Name a function of MySQL used to give position of the first occurrence of a string2 in string1.
What will be returned by the given query? SELECT MID('BoardExamination', 2, 4) = ______.
Which of the following is not a date function?
Which of the following is not a text function?
Which function will be used to remove only the trailing spaces from a string?
The string function that returns the index of the first occurrence of substring is ______.
What is the general format of UPPER() return type?
Site any two differences between Single Row Functions and Aggregate Functions.
Write the name of the functions to perform the following operation:
To display the day like “Monday”, and “Tuesday”, from the date when India got independence.
Write the name of the functions to perform the following operation:
To display the specified number of characters from a particular position of the given string.
Write the output produced by the following SQL statement:
SELECT LENGTH("Informatics Practices");
Write the output produced by the following SQL statement:
SELECT YEAR(“1979/11/26”),
MONTH(“1979/11/26”), DAY(“1979/11/26”), MONTHNAME(“1979/11/26”);
Which function is used to display the total number of records from a table in a database?
Which type of values will not be considered by SQL while executing the following statement?
SELECT COUNT(column name) FROM inventory;
If column “Fees” contains the data set (5000,8000,7500,5000,8000), what will be the output after the execution of the given query?
SELECT SUM (DISTINCT Fees) FROM student;
Which one of the following is not an aggregate function?
Which one of the following functions are used to find the largest value from the given data in MySQL?
In SQL, which function is used to display the current date and time?
Write outputs for SQL queries that are based on the given table PURCHASE:
| TABLE: PURCHASE | ||||
| CNO | CNAME | CITY | QUANTITY | DOP |
| C01 | GURPREET | NEW DELHI | 150 | 2022-06-11 |
| C02 | MALIKA | HYDERABAD | 10 | 2022-02-19 |
| C03 | NADAR | DALHOUSIE | 100 | 2021-12-04 |
| C04 | SAHIB | CHANDIGARH | 50 | 2021-10-10 |
| C05 | MEHAK | CHANDIGARH | 15 | 2021-10-20 |
- SELECT LENGTH(CNAME) FROM PURCHASE WHERE QUANTITY>100;
- SELECT CNAME FROM PURCHASE WHERE MONTH(DOP) = 3;
- SELECT MOD (QUANTITY, DAY(DOP)) FROM PURCHASE WHERE CITY = ‘CHANDIGARH’;
Write suitable SQL query for the following:
Display 7 characters extracted from the 7th left character onwards from the string ‘INDIA SHINING’.
Write suitable SQL query for the following:
Round off the value 23.78 to one decimal place.
Write suitable SQL query for the following:
Display the remainder of 100 divided by 9.
Explain the following SQL function using a suitable example.
TRIM()
Explain the following SQL function using a suitable example.
MID()
Explain the following SQL function using a suitable example.
POWER()
Shreya, a database administrator has designed a database for a clothing shop. Help her by writing answers to the following questions based on the given table:
| TABLE: CLOTH | |||||
| CCODE | CNAME | SIZE | COLOR | PRICE | DOP |
| C001 | JEANS | XL | BLUE | 990 | 2022-01-21 |
| C002 | T-SHIRT | M | RED | 599 | 2021-12-12 |
| C003 | TROUSER | M | GREY | 399 | 2021-11-10 |
| C004 | SAREE | FREE | GREEN | 1299 | 2019-11-12 |
| C005 | KURTI | L | WHITE | 399 | 2021-12-07 |
- Write a query to display cloth names in lowercase.
- Write a query to display the lowest price of the clothes.
- Write a query to count the total number of clothes purchased in medium size.
OR
Write a query to count the year-wise total number of clothes purchased.
