WEEK 4

Question 1

Answer: SQL stands for Structured Query Language and is a query language used to manage and manipulate relational databases.

Answer 1

Question: What is SQL?

Question 2

Question: What is the difference between DDL and DML?

Answer 2

Answer: DDL stands for Data Definition Language and is used to define the structure and schema of a database. DML stands for Data Manipulation Language and is used to manipulate the data stored in a database.

Question 3

Question: What does the SQL statement “SELECT * from product;” do?

Answer 3

Answer: This SQL statement selects all columns and rows from the “product” table.

Question 4

Question: What does the * symbol represent in the SQL statement “SELECT * from product;”?
.

Answer 4

Answer: The * symbol represents all columns in the specified table

Question 5

Question: How can you select only specific columns in a SQL query?

Answer 5

Answer: You can specify the column names in the SELECT statement instead of using the * symbol.

Question 6

Question: What is the purpose of the “–” symbol in SQL?

Answer 6

Answer: The “–” symbol is used to indicate a comment in SQL code.

Question 7

Question: What are logical operators in SQL?

Answer 7

Answer: Logical operators are used in SQL to combine conditions in a query. The two most common operators are “AND” and “OR”.

Question 8

Question: How can you concatenate two columns in a SQL query?

Answer 8

Answer: You can concatenate two columns by using the + operator in between them, like this: SELECT CUS_FNAME +’ ‘+ CUS_LNAME FROM CUSTOMER;

Question 9

Question: What is the purpose of the DISTINCT keyword in SQL?

Answer 9

Answer: The DISTINCT keyword is used to remove duplicates from the results of a query and only show unique values.

Question 10

Question: How can you order the results of a SQL query?

Answer 10

Answer: You can use the ORDER BY keyword followed by the column name to sort the results of a query. By default, the results are sorted in ascending order, but you can add the “DESC” keyword to sort in descending order.

Question 11

Question: What is the purpose of the BETWEEN keyword in SQL?

Answer 11

Answer: The BETWEEN keyword is used to filter results within a specified range of values.

Question 12

What is DML?

.

Answer 12

Answer: DML is a data manipulation language used to insert, update, delete, and retrieve information

Question 13

What is DDL?

Answer 13

Answer: DDL is a data definition language used to create objects (tables, indexes, views) and access rights (users).

Question 14

What is TCL?

Answer 14

Answer: TCL is a transaction control language.

Question 15

What is DCL?

Answer 15

Answer: DCL is a data control language used for user permission - who can do what.

Question 16

What are some data types?

Answer 16

Answer: Data types include character (string), numeric (int, float), date/time, boolean (yes/no), and GUID.

Question 17

What is the syntax for the SELECT keyword?

Answer 17

Answer: The syntax for the SELECT keyword is SELECT (data fields) FROM (tablename).

Question 18

What is an alias in SQL?

Answer 18

Answer: An alias in SQL is used to make field names prettier. It is a syntax that allows you to rename a column in a table with another name.

Question 19

To create a table, you
will need:

Answer 19

1. A table name
2. Names for all
   columns
3. Data type for each
   column
4. Applicable
   constraints

Question 20

DDL (Data Definition Language) commands:

Answer 20

NOT NULL
PRIMARY KEY
FORIEGN KEY
DEFAULT
CHECK
CREATE: used to create a new database object such as a table, index, view, or stored procedure.
ALTER: used to modify the structure of an existing database object.
DROP: used to delete an existing database object.
TRUNCATE: used to delete all the data from a table without deleting the table structure.
RENAME: used to rename an existing database object.
GRANT: used to grant specific privileges to a user or role.
REVOKE: used to revoke privileges that were previously granted.

Question 21

DML (Data Manipulation Language) commands:

Answer 21

SELECT: used to retrieve data from a database table.
INSERT: used to insert new data into a database table.
UPDATE: used to modify existing data in a database table.
DELETE: used to delete data from a database table.
MERGE: used to combine data from two tables into a single table.
CALL: used to execute a stored procedure or function.
LOCK: used to lock a table or row to prevent other users from modifying the data.

Question 22

Character: This data type is used to store strings of characters, such as names, addresses, and other textual data. The maximum length of a character data type is determined by the database system.

Numeric: This data type is used to store numeric data, such as integers or decimal numbers. There are different types of numeric data types in SQL, such as INTEGER, SMALLINT, BIGINT, DECIMAL (L,D), and FLOAT.

Date/time: This data type is used to store date and time data. The SQL standard defines two data types for date/time data: DATE for storing dates and TIMESTAMP for storing both dates and times.

Answer 22

Character: This data type is used to store strings of characters, such as names, addresses, and other textual data. The maximum length of a character data type is determined by the database system.

Numeric: This data type is used to store numeric data, such as integers or decimal numbers. There are different types of numeric data types in SQL, such as INTEGER, SMALLINT, BIGINT, DECIMAL, and FLOAT.

Date/time: This data type is used to store date and time data. The SQL standard defines two data types for date/time data: DATE for storing dates and TIMESTAMP for storing both dates and times.