Tag: databases
Questions Related to databases
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UPDATE
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SELECT
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INSERT
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INVERT
To solve this question, the user needs to have basic knowledge of SQL keywords and clauses. SQL (Structured Query Language) is a standard language for managing relational databases. It is important to know which words and clauses are part of SQL and which are not.
Now, let's go through each option and explain why it is right or wrong:
A. UPDATE: This is a SQL keyword that is used to modify existing records in a table.
B. SELECT: This is a SQL keyword that is used to query data from a table.
C. INSERT: This is a SQL keyword that is used to insert new records into a table.
D. INVERT: This is not a SQL keyword or SQL clause. It is not used in SQL to perform any operation.
Therefore, the answer is: D. INVERT.
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insert and delete only
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update and delete only
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update, delete and insert
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insert and update only
Which SQL statement selects all rows from a table called Products and orders the result set by ProductID column?
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SELECT * FROM Products ORDER BY ProductID
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SELECT * FROM Products WHERE ProductID > 200
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SELECT * FROM Products ORDERED BY ProductID
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SELECT ProductID FROM Products
What does the following SQL statement do: SELECT Customer, COUNT(Order) FROM Sales GROUP BY Customer HAVING COUNT(Order) >5
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Selects all Customers from the Sales table
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Selects all customers from table Sales that have made more than 5 orders.
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Selects the total number of orders from the Sales table, if this number is greater than 5
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Selects no records
AI Explanation
To answer this question, we need to understand the different components of the SQL statement:
SELECT Customer, COUNT(Order): This part of the statement selects the 'Customer' column and counts the number of occurrences of 'Order' for each customer.
FROM Sales: This specifies that we are selecting data from the 'Sales' table.
GROUP BY Customer: This groups the data by the 'Customer' column, so that we get the count of orders for each customer separately.
HAVING COUNT(Order) > 5: This filters the results and only selects the records where the count of orders for a customer is greater than 5.
Let's go through each option to understand why it is correct or incorrect:
Option A) Selects all Customers from the Sales table - This option is incorrect because the statement is not selecting all customers. It is selecting customers who have made more than 5 orders.
Option B) Selects all customers from table Sales that have made more than 5 orders - This option is correct because the statement is grouping the data by customer and selecting only those customers who have made more than 5 orders.
Option C) Selects the total number of orders from the Sales table if this number is greater than 5 - This option is incorrect because the statement is not selecting the total number of orders. It is selecting customers who have made more than 5 orders.
Option D) Selects no records - This option is incorrect because the statement will select records if there are customers who have made more than 5 orders.
The correct answer is B) Selects all customers from the table Sales that have made more than 5 orders. This option is correct because the SQL statement filters the results to only include customers who have made more than 5 orders.
What is a foreign key?
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The foreign key is a column that can have NULL values.
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The foreign key is a SQL locking mechanism.
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A foreign key is a key field (column) in a database table, which relates the table to another table where the key is a primary key. The primary - foreign key relations are used to cross-reference database tables.
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The foreign key is a column that should be primary key for that table.
To understand what a foreign key is, the user needs to have a basic understanding of database design.
The correct answer is:
C. A foreign key is a key field (column) in a database table, which relates the table to another table where the key is a primary key. The primary-foreign key relations are used to cross-reference database tables.
Explanation of options:
A. This option is incorrect because a foreign key cannot have NULL values. A foreign key must reference a valid primary key in another table.
B. This option is incorrect because a foreign key is not related to SQL locking mechanisms. SQL locking mechanisms are used to manage concurrent access to data.
D. This option is incorrect because a foreign key cannot be a primary key for that table. A primary key is a unique identifier for a table, while a foreign key is used to reference a primary key in another table.
Which SQL statement inserts data into a table called Projects?
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INSERT Projects VALUES ('Content Development', 'Website content development project')
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INSERT Projects ('Content Development', 'Website content development project')
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INSERT INTO Projects (ProjectName, ProjectDescription) VALUES ('Content Development', 'Website content development project')
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SAVE INTO Projects (ProjectName, ProjectDescription) VALUES ('Content Development', 'Website content development project')
AI Explanation
To answer this question, we need to understand the syntax of the SQL INSERT statement. The correct statement should have the following format:
INSERT INTO table_name (column1, column2, ...) VALUES (value1, value2, ...);
Let's go through each option to determine the correct statement:
Option A) INSERT Projects VALUES ('Content Development', 'Website content development project') - This option is incorrect because it is missing the "INTO" keyword before the table name.
Option B) INSERT Projects ('Content Development', 'Website content development project') - This option is incorrect because it is missing the "INTO" keyword before the table name, and it does not specify the column names.
Option C) INSERT INTO Projects (ProjectName, ProjectDescription) VALUES ('Content Development', 'Website content development project') - This option is correct. It uses the correct syntax of the INSERT statement, specifying the table name (Projects), column names (ProjectName, ProjectDescription), and the corresponding values.
Option D) SAVE INTO Projects (ProjectName, ProjectDescription) VALUES ('Content Development', 'Website content development project') - This option is incorrect because it uses the incorrect keyword "SAVE" instead of "INSERT INTO".
The correct answer is Option C. This option is correct because it follows the correct syntax of the INSERT statement, specifying the table name (Projects), column names (ProjectName, ProjectDescription), and the corresponding values.
Which of the following SQL statements is correct?
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SELECT FROM Sales WHERE Date BETWEEN ('10/12/2005', '01/01/2006')
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SELECT * FROM Sales WHERE Date BETWEEN '10/12/2005' AND '01/01/2006'
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SELECT FROM Sales WHERE Date BETWEEN '10/12/2005' AND '01/01/2006'
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SELECT * FROM Sales WHERE Date BETWEEN ('10/12/2005', '01/01/2006')
AI Explanation
To answer this question, let's go through each option to understand why it is correct or incorrect:
Option A) SELECT FROM Sales WHERE Date BETWEEN ('10/12/2005', '01/01/2006') - This option is incorrect because the syntax is incorrect. The correct syntax for the BETWEEN operator is "value BETWEEN value1 AND value2".
Option B) SELECT * FROM Sales WHERE Date BETWEEN '10/12/2005' AND '01/01/2006' - This option is correct because it uses the correct syntax for the BETWEEN operator. The date values are enclosed in single quotes and separated by the keyword "AND".
Option C) SELECT FROM Sales WHERE Date BETWEEN '10/12/2005' AND '01/01/2006' - This option is incorrect because the SELECT statement is missing the column names to select from the Sales table.
Option D) SELECT * FROM Sales WHERE Date BETWEEN ('10/12/2005', '01/01/2006') - This option is incorrect because the date values are enclosed in parentheses, which is not the correct syntax for the BETWEEN operator.
The correct answer is B. This option is correct because it uses the correct syntax for the BETWEEN operator and selects all columns from the Sales table where the Date is between '10/12/2005' and '01/01/2006'.
If you join a table to itself, what kind of join are you using?
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Self Join
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Selective Join.
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Outer Join
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You can't join a table to itself.
Which of the following is a reserved SQL keyword?
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GROWN
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FROM
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UPDATING
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DELETING
To solve this question, the user needs to know what a reserved SQL keyword is. A reserved SQL keyword is a word that has a special meaning in SQL and cannot be used as a name for a table, column, or other database object.
Now, let's go through each option and explain why it is right or wrong:
A. GROWN: This option is incorrect because "GROWN" is not a reserved SQL keyword. It is not a commonly used SQL keyword and can be used as a name for a table, column, or other database object.
B. FROM: This option is correct. "FROM" is a reserved SQL keyword that is used to specify the table or tables from which to retrieve data in a SELECT statement. It is a commonly used SQL keyword and cannot be used as a name for a table, column, or other database object.
C. UPDATING: This option is incorrect because "UPDATING" is not a reserved SQL keyword. While "UPDATE" is a reserved SQL keyword that is used to modify data in a table, "UPDATING" is not a commonly used SQL keyword and can be used as a name for a table, column, or other database object.
D. DELETING: This option is incorrect because "DELETING" is not a reserved SQL keyword. While "DELETE" is a reserved SQL keyword that is used to remove rows from a table, "DELETING" is not a commonly used SQL keyword and can be used as a name for a table, column, or other database object.
The Answer is: B
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Use SELECT COUNT(*)...in db2 query
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Use SELECT DISTINCT...in db2 query
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Use SELECT MAX(...)...in db2 query
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Use SELECT ROWNUM(*)...in db2 query