SQL QUARY EXAMPLES

 


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mysql> SHOW DATABASES;

+-------------------------+

| Database                |

+-------------------------+

| aktu_ka_database        |

| college_ka_database     |

| dosti                   |

| information_schema      |

| jai_bajgrang_bali_ka_db |

| kishan_ka_database      |

| library                 |

| library_ka_database     |

| mysql                   |

| performance_schema      |

| ravi_kumar_singh_db     |

| ravi_singh db           |

| student_db              |

| student_ka_database     |

| students_details_db     |

| sys                     |

+-------------------------+

16 rows in set (0.02 sec)


mysql> DROP dosti;

ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'dosti' at line 1

mysql> drop database dosti;

Query OK, 1 row affected (0.10 sec)


mysql> show databases;

+-------------------------+

| Database                |

+-------------------------+

| aktu_ka_database        |

| college_ka_database     |

| information_schema      |

| jai_bajgrang_bali_ka_db |

| kishan_ka_database      |

| library                 |

| library_ka_database     |

| mysql                   |

| performance_schema      |

| ravi_kumar_singh_db     |

| ravi_singh db           |

| student_db              |

| student_ka_database     |

| students_details_db     |

| sys                     |

+-------------------------+

15 rows in set (0.00 sec)


mysql> drop databases sys,mysql;

ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'databases sys,mysql' at line 1

mysql> drop databases dosti;

ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'databases dosti' at line 1

mysql> drop databases sys;

ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'databases sys' at line 1

mysql> DROP DATABASE sys;

Query OK, 101 rows affected (0.41 sec)


mysql> show databases;

+-------------------------+

| Database                |

+-------------------------+

| aktu_ka_database        |

| college_ka_database     |

| information_schema      |

| jai_bajgrang_bali_ka_db |

| kishan_ka_database      |

| library                 |

| library_ka_database     |

| mysql                   |

| performance_schema      |

| ravi_kumar_singh_db     |

| ravi_singh db           |

| student_db              |

| student_ka_database     |

| students_details_db     |

+-------------------------+

14 rows in set (0.00 sec)


mysql> CREATE DATABASE Data_Science;

Query OK, 1 row affected (0.01 sec)


mysql> show databases;

+-------------------------+

| Database                |

+-------------------------+

| aktu_ka_database        |

| college_ka_database     |

| data_science            |

| information_schema      |

| jai_bajgrang_bali_ka_db |

| kishan_ka_database      |

| library                 |

| library_ka_database     |

| mysql                   |

| performance_schema      |

| ravi_kumar_singh_db     |

| ravi_singh db           |

| student_db              |

| student_ka_database     |

| students_details_db     |

+-------------------------+

15 rows in set (0.00 sec)


mysql> use database data_science;

ERROR 1049 (42000): Unknown database 'database'

mysql> use data_science;

Database changed

mysql> create table data_science_student_table;

ERROR 4028 (HY000): A table must have at least one visible column.

mysql> create table datasciencestudent;

ERROR 4028 (HY000): A table must have at least one visible column.

mysql> use data_science;

Database changed

mysql> create table data;

ERROR 4028 (HY000): A table must have at least one visible column.

mysql> CREATE TABLE data(

    -> id INT UNIQUE

    -> );

Query OK, 0 rows affected (0.05 sec)


mysql> INSERT INTO data VALUES(101);

Query OK, 1 row affected (0.01 sec)


mysql> INSERT INTO data VALUES(102);

Query OK, 1 row affected (0.01 sec)


mysql> SELECT * FROM data;

+------+

| id   |

+------+

|  101 |

|  102 |

+------+

2 rows in set (0.00 sec)


mysql> INSERT INTO data VALUES

    ->

    -> (103);

Query OK, 1 row affected (0.00 sec)


mysql> INSERT INTO data VALUES(103);

ERROR 1062 (23000): Duplicate entry '103' for key 'data.id'

mysql> INSERT INTO data VALUES(104);

Query OK, 1 row affected (0.00 sec)


mysql> SELECT * FROM data;

+------+

| id   |

+------+

|  101 |

|  102 |

|  103 |

|  104 |

+------+

4 rows in set (0.00 sec)


mysql> CREATE TABLE data(

    -> name VARCHAR(50),

    -> rollno INT NOT NULL);

ERROR 1050 (42S01): Table 'data' already exists

mysql> SELECT * TABLE FROM data_science;

ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'TABLE FROM data_science' at line 1

mysql> alter table data add column name varchar(50) after id;

Query OK, 0 rows affected (0.03 sec)

Records: 0  Duplicates: 0  Warnings: 0


mysql> select*from data;

+------+------+

| id   | name |

+------+------+

|  101 | NULL |

|  102 | NULL |

|  103 | NULL |

|  104 | NULL |

+------+------+

4 rows in set (0.00 sec)


mysql>

mysql> alter table data  add column rollno int  before name;

ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'before name' at line 1

mysql> alter table data  add column rollno int  after name;

Query OK, 0 rows affected (0.02 sec)

Records: 0  Duplicates: 0  Warnings: 0


mysql> select*from data;

+------+------+--------+

| id   | name | rollno |

+------+------+--------+

|  101 | NULL |   NULL |

|  102 | NULL |   NULL |

|  103 | NULL |   NULL |

|  104 | NULL |   NULL |

+------+------+--------+

4 rows in set (0.00 sec)


mysql> select rollno from data;

+--------+

| rollno |

+--------+

|   NULL |

|   NULL |

|   NULL |

|   NULL |

+--------+

4 rows in set (0.00 sec)


mysql> select name from data values

    -> ("Ravi singh");

ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'values

("Ravi singh")' at line 1

mysql>  INSERT INTO data (name, rollno) VALUES (value1, value2, value3, etc);

ERROR 1136 (21S01): Column count doesn't match value count at row 1

mysql> INSERT INTO data (name, rollno)

    -> VALUES("RAVI KUMAR SINGH",67),

    -> VALUES("KISHAN KUMAR PRAJAPATI",43),

    -> VALUES("RAHUL SINGH",22);

ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'VALUES("KISHAN KUMAR PRAJAPATI",43),

VALUES("RAHUL SINGH",22)' at line 3

mysql>  INSERT INTO data (name, rollno)

    ->  VALUES("RAVI KUMAR SINGH",67);

Query OK, 1 row affected (0.01 sec)


mysql> SELECT*FROM data;

+------+------------------+--------+

| id   | name             | rollno |

+------+------------------+--------+

|  101 | NULL             |   NULL |

|  102 | NULL             |   NULL |

|  103 | NULL             |   NULL |

|  104 | NULL             |   NULL |

| NULL | RAVI KUMAR SINGH |     67 |

+------+------------------+--------+

5 rows in set (0.00 sec)


mysql> create database if  not exist college;

ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'exist college' at line 1

mysql> CREATE DATABASE IF NOT EXISTS college;

Query OK, 1 row affected (0.01 sec)


mysql> show databases;

+-------------------------+

| Database                |

+-------------------------+

| aktu_ka_database        |

| college                 |

| college_ka_database     |

| data_science            |

| information_schema      |

| jai_bajgrang_bali_ka_db |

| kishan_ka_database      |

| library                 |

| library_ka_database     |

| mysql                   |

| performance_schema      |

| ravi_kumar_singh_db     |

| ravi_singh db           |

| student_db              |

| student_ka_database     |

| students_details_db     |

+-------------------------+

16 rows in set (0.00 sec)


mysql> CREATE DATABASE IF NOT EXISTS college;

Query OK, 1 row affected, 1 warning (0.00 sec)


mysql> show databases;

+-------------------------+

| Database                |

+-------------------------+

| aktu_ka_database        |

| college                 |

| college_ka_database     |

| data_science            |

| information_schema      |

| jai_bajgrang_bali_ka_db |

| kishan_ka_database      |

| library                 |

| library_ka_database     |

| mysql                   |

| performance_schema      |

| ravi_kumar_singh_db     |

| ravi_singh db           |

| student_db              |

| student_ka_database     |

| students_details_db     |

+-------------------------+

16 rows in set (0.00 sec)


mysql> CREATE DATABASE IF NOT EXISTS prema;

Query OK, 1 row affected (0.01 sec)


mysql> show databases;

+-------------------------+

| Database                |

+-------------------------+

| aktu_ka_database        |

| college                 |

| college_ka_database     |

| data_science            |

| information_schema      |

| jai_bajgrang_bali_ka_db |

| kishan_ka_database      |

| library                 |

| library_ka_database     |

| mysql                   |

| performance_schema      |

| prema                   |

| ravi_kumar_singh_db     |

| ravi_singh db           |

| student_db              |

| student_ka_database     |

| students_details_db     |

+-------------------------+

17 rows in set (0.00 sec)


mysql> create database if not exists madhubala;

Query OK, 1 row affected (0.01 sec)


mysql> show databases;

+-------------------------+

| Database                |

+-------------------------+

| aktu_ka_database        |

| college                 |

| college_ka_database     |

| data_science            |

| information_schema      |

| jai_bajgrang_bali_ka_db |

| kishan_ka_database      |

| library                 |

| library_ka_database     |

| madhubala               |

| mysql                   |

| performance_schema      |

| prema                   |

| ravi_kumar_singh_db     |

| ravi_singh db           |

| student_db              |

| student_ka_database     |

| students_details_db     |

+-------------------------+

18 rows in set (0.00 sec)


mysql> create table emp(

    -> id int ,

    -> salery int default 25000);

Query OK, 0 rows affected (0.04 sec)


mysql> insert into emp(id) values(101);

Query OK, 1 row affected (0.01 sec)


mysql> select *from emp;

+------+--------+

| id   | salery |

+------+--------+

|  101 |  25000 |

+------+--------+

1 row in set (0.00 sec)


mysql>

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