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Questions and Answers
What is the purpose of the SQL SELECT statement?
What is the purpose of the SQL SELECT statement?
- To update existing records in a table
- To delete records from a table
- To retrieve data from one or more tables (correct)
- To insert new records into a table
What does the WHERE clause do in an SQL statement?
What does the WHERE clause do in an SQL statement?
- It groups rows that have the same values
- It specifies the order of the results
- It filters records based on a specified condition (correct)
- It retrieves all columns from a table
In the SQL INSERT statement, what does the VALUES clause specify?
In the SQL INSERT statement, what does the VALUES clause specify?
- The order in which the data will be displayed
- The table from which the data is retrieved
- The actual data to be inserted into the specified columns (correct)
- The specific columns to be updated
Which SQL command will modify existing records in a table?
Which SQL command will modify existing records in a table?
What will happen if the WHERE clause is omitted in an UPDATE statement?
What will happen if the WHERE clause is omitted in an UPDATE statement?
Which of the following is a valid example of a SQL SELECT statement?
Which of the following is a valid example of a SQL SELECT statement?
In an SQL DELETE statement, what does the WHERE clause determine?
In an SQL DELETE statement, what does the WHERE clause determine?
What does the GROUP BY clause do in an SQL query?
What does the GROUP BY clause do in an SQL query?
What will happen if the DELETE statement does not include a WHERE clause?
What will happen if the DELETE statement does not include a WHERE clause?
Which of the following SQL statements correctly selects employees with salaries between 500 and 700?
Which of the following SQL statements correctly selects employees with salaries between 500 and 700?
What does the SQL WHERE clause allow you to do?
What does the SQL WHERE clause allow you to do?
Which symbol can be used in a SQL statement to match any single character?
Which symbol can be used in a SQL statement to match any single character?
What will the statement 'SELECT CODE FROM EMPLOYEES WHERE NAME IN ('John', 'Doe')' return?
What will the statement 'SELECT CODE FROM EMPLOYEES WHERE NAME IN ('John', 'Doe')' return?
How would you update an employee's surname in the EMPLOYEES table where the first name is 'John'?
How would you update an employee's surname in the EMPLOYEES table where the first name is 'John'?
What does the SQL statement 'DROP TABLE employees' do?
What does the SQL statement 'DROP TABLE employees' do?
Which SQL command would you use to find all employees who do not have a store ID assigned?
Which SQL command would you use to find all employees who do not have a store ID assigned?
Flashcards
SQL UPDATE
SQL UPDATE
Used to modify existing data in a table. Specify the table, column to update, new value, and matching condition (WHERE).
SQL DELETE
SQL DELETE
Removes rows from a table based on a specified condition. If no condition is given, it deletes all rows.
SQL DROP TABLE
SQL DROP TABLE
Permanently removes a table and all of its data from the database.
SQL WHERE clause (equality)
SQL WHERE clause (equality)
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SQL WHERE clause (BETWEEN)
SQL WHERE clause (BETWEEN)
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SQL WHERE clause (IN)
SQL WHERE clause (IN)
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SQL WHERE clause (LIKE)
SQL WHERE clause (LIKE)
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SQL NULL
SQL NULL
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SQL WHERE clause (IS NULL)
SQL WHERE clause (IS NULL)
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SQL wildcard (%)
SQL wildcard (%)
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SQL wildcard (_)
SQL wildcard (_)
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SQL SELECT Statement
SQL SELECT Statement
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SQL SELECT *
SQL SELECT *
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SQL SELECT with columns
SQL SELECT with columns
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SQL WHERE Clause
SQL WHERE Clause
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SQL INSERT Statement
SQL INSERT Statement
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SQL UPDATE Statement
SQL UPDATE Statement
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SQL DELETE Statement
SQL DELETE Statement
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SQL FROM Clause
SQL FROM Clause
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SQL Single Quotes
SQL Single Quotes
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SQL Double Quotes
SQL Double Quotes
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SQL GROUP BY Clause
SQL GROUP BY Clause
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SQL ORDER BY Clause
SQL ORDER BY Clause
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SQL HAVING Clause
SQL HAVING Clause
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Study Notes
Database Usage, SQL
- SQL is used for manipulating and retrieving data from databases.
- DML (Data Manipulation Language) statements are used to manage data within a database.
DML Statements
- SELECT: Retrieves data from one or more tables.
- INSERT: Adds new rows into a table.
- UPDATE: Modifies existing rows in a table.
- DELETE: Removes existing rows from a table.
- FROM: Specifies the table(s) from which to retrieve data.
- WHERE: Filters data based on a specified condition.
- GROUP BY: Groups rows with the same values in a column(s).
- ORDER BY: Sorts the results based on one or more columns.
- HAVING: Filters grouped data based on a condition.
SQL SELECT Statement
- Used to retrieve data from a table or tables.
- The result is a result-set, which is a table form.
- Syntax:
SELECT column1, column2, ... FROM table_name;SELECT * FROM table_name;(* means all columns*)
SQL WHERE Clause
- Filters data based on a condition.
- Syntax:
SELECT column1, column2, ... FROM table_name WHERE condition;
SQL INSERT Statement
- Used to add new rows to a table.
- Syntax:
INSERT INTO table_name (column1, column2, ...) VALUES (value1, value2, ...);
SQL UPDATE Statement
- Used to modify existing rows in a table.
- Syntax:
UPDATE table_name SET column1 = value1, column2 = value2, ... WHERE condition;
SQL DELETE Statement
- Used to remove rows from a table.
- Syntax:
DELETE FROM table_name WHERE condition;
SQL WHERE Clause (Operators)
- BETWEEN: Matches values within a specified range.
- IN: Matches values in a list.
- LIKE: Matches patterns.
%matches any sequence of characters,_matches any single character. - NOT: Negates a condition.
- AND: Combines conditions that must both be true
- OR: Combines conditions where at least one must be true
- IS NULL: Checks for null values.
SQL GROUP BY
- Groups rows that have similar values in specified columns.
- Used with aggregate functions.
- Aggregate Functions:
- AVG(): Calculates the average.
- COUNT(): Counts the number of rows.
- MAX(): Finds the maximum value.
- MIN(): Finds the minimum value.
- SUM(): Calculates the sum
SQL HAVING Clause
- Filters grouped data based on a condition.
- Used after a GROUP BY clause.
SQL Additional functions
- DISTINCT: Retrieves only unique values.
- LOWER: Converts strings to lowercase.
- UPPER: Converts strings to uppercase.
- CONCAT: Concatenates strings.
SQL Syntax summary
- General syntax:
SELECT columns FROM table WHERE condition GROUP BY grouping_columns HAVING condition ORDER BY ordering_columns
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Description
This quiz covers the manipulation and retrieval of data using SQL, focusing on Data Manipulation Language (DML) statements. Participants will learn about key commands such as SELECT, INSERT, UPDATE, and DELETE, along with filtering and sorting options to manage database queries effectively.
