SQL T2

___________ and __________constraints form the core of the PRIMARY KEY constraint.

• NOT NULL , CHECK
• CHECK ,UNIQUE
• NOT NULL , FOREIGN KEY
• NOT NULL , UNIQUE

To modify the students table and to add a primary key on the student_id Column, Which statement must be used to accomplishes this task? Note: The table is currently empty.

• alter table students add primary key (student_id);
• Alter table students add constraint primary key (student_id);
• Alter table students add constraint stud_id_pk primary key (student_id);
• A&C BOTH

Which of the following is TRUE about UNIQUE constraint?

• In columns that are subject to the UNIQUE constraint, duplicate values are not allowed.
• Unique values will always be present in the column containing the unique constraint.
• A single table can have more than one unique constraint, since it can be applied to more than one column.
• All of the above

Purpose of foreign key constraint in SQL Server is __________

• FOREIGN KEY constraints identify and enforce the relationships between tables
• A foreign key in one table points to a candidate key in another table
• You cannot insert a row with a foreign key value, except NULL, if there is no candidate key with that value
• None of the mentioned

Which of the following is the correct syntax for using the AVG() function in PostgreSQL?

• SELECT AVG(column_name) FROM table_name;
• SELECT AVG FROM column_name FROM table_name;
• SELECT AVG(table_name) FROM column_name;
• SELECT AVG(column_name, table_name) FROM table_name;

What does the COUNT function in PostgreSQL do?

• Counts the occurrences of a specific value in a column.
• Calculates the average value of a numeric column.
• Returns the highest value in a column.
• find the number of values in the specified column excluding NULL values

What is the purpose of the MAX function in PostgreSQL?

• Retrieves the highest value from a specified column.
• Calculates the average value of a numeric column.
• Returns the number of rows in a specified table or view.
• Counts the occurrences of a specific value in a column.

How can you use the MIN function to retrieve the lowest value from a column?

• MIN(value) WHERE column_name;
• MIN(value, column_name)
• MIN(column_name)
• MIN(column_name) ORDER BY value

Which is not a numeric/math function in SQL?

• ABS
• SQRT
• FLOOR
• COUNT

What is the output value of query given below? SELECT ROUND(3.14159, 2);

• 3.141
• 3.15
• 3.14
• 3.2