SQL Commands, Functions, and Operators Quiz

SQL Components

• SQL consists of data types, operators, DDL (Data Definition Language) commands, and DML (Data Manipulation Language) commands.

DDL Commands

• CREATE command: used to create tables
• ALTER command: used to modify existing tables
• DROP command: used to delete tables

DML Commands

• SELECT command: used to retrieve data from tables
• INSERT command: used to add new data to tables
• DELETE command: used to delete data from tables
• UPDATE command: used to modify existing data in tables

Query Clauses

• ORDER BY clause: used to sort data in ascending or descending order
• GROUP BY clause: used to group data based on one or more columns
• HAVING clause: used to filter grouped data based on conditions

Views

• A view is a virtual table based on the result of a query
• DML operations can be performed on views

Functions

Numeric Functions

• ABS: returns the absolute value of a number
• MOD: returns the remainder of a division operation
• FLOOR: returns the largest integer less than or equal to a number
• CEIL: returns the smallest integer greater than or equal to a number
• TRUNC: returns the truncated value of a number
• SQRT: returns the square root of a number
• SIGN: returns the sign of a number (1 if positive, -1 if negative, 0 if zero)
• SIN, COS, LOG, EXP: returns the sine, cosine, logarithm, and exponential of a number, respectively
• LEAST, GREATEST: returns the smallest or largest of two or more values

Group Functions

• AVG: returns the average value of a set of numbers
• MAX: returns the maximum value of a set of numbers
• MIN: returns the minimum value of a set of numbers
• SUM: returns the sum of a set of numbers
• COUNT: returns the count of a set of values

Character Functions

• LENGTH: returns the length of a string
• LOWER, UPPER: returns the lowercase or uppercase version of a string
• INITCAP: returns the capitalized version of a string
• INSTR: returns the position of a substring within a string
• SUBSTR: returns a subset of a string
• LPAD, RPAD: returns a string padded with a specified character on the left or right
• LTRIM, RTRIM: returns a string with leading or trailing characters removed
• DECODE: returns a decoded value based on a set of conditions
• SOUNDEX: returns the soundex code of a string

Conversion Functions

• TO-NUMBER: converts a string to a number
• TO-CHAR: converts a number to a string

Joins and Unions

• Joins: combine data from multiple tables based on a common column
• Unions: combine the results of multiple queries into a single result set