Which product is returned in a join query have no join condition?

Which product is returned in a join query have no join condition?

Discussion Forum

Que.	Which product is returned in a join query have no join condition:
b.	Cartesian
c.	Both Equijoins and Cartesian
d.	None of the mentioned
	Answer:Cartesian

What is the difference between Equi join and natural join?

Equi Join is a join using one common column (referred to in the “on” clause). Natural Join is an implicit join clause based on the common columns in the two tables being joined. Common columns are columns that have the same name in both tables.

What are the after triggers?

What are the after triggers? Explanation: AFTER TRIGGERS can be classified further into three types as: AFTER INSERT Trigger, AFTER UPDATE Trigger, AFTER DELETE Trigger. Explanation: Example : declare @empid int; where empid is the variable.

Which of the following conditions has to be satisfied for inner join to work?

Explanation: INNER JOIN: Returns all rows when there is at least one match in BOTH tables. 3. Explanation: Join can be replaced by inner join.

What are the different in triggers?

In SQL Server we can create four types of triggers Data Definition Language (DDL) triggers, Data Manipulation Language (DML) triggers, CLR triggers, and Logon triggers.

What are the join types in join condition?

A JOIN is a means for combining columns from one (self-join) or more tables by using values common to each. ANSI-standard SQL specifies five types of JOIN : INNER , LEFT OUTER , RIGHT OUTER , FULL OUTER and CROSS .

When to use left join and right join?

The LEFT JOIN includes all records from the left side and matched rows from the right table, whereas RIGHT JOIN returns all rows from the right side and unmatched rows from the left table….LEFT JOIN vs. RIGHT JOIN.

LEFT JOIN	RIGHT JOIN
It is also known as LEFT OUTER JOIN.	It is also called as RIGHT OUTER JOIN.

How is full join different from left and right join?

LEFT JOIN: returns all rows from the left table, even if there are no matches in the right table. RIGHT JOIN: returns all rows from the right table, even if there are no matches in the left table. FULL JOIN: It combines the results of both left and right outer joins. We have two tables with the following values.

Which join is faster in SQL?

9 Answers. A LEFT JOIN is absolutely not faster than an INNER JOIN . In fact, it’s slower; by definition, an outer join ( LEFT JOIN or RIGHT JOIN ) has to do all the work of an INNER JOIN plus the extra work of null-extending the results.

Why use LEFT JOIN instead of inner join?

You’ll use INNER JOIN when you want to return only records having pair on both sides, and you’ll use LEFT JOIN when you need all records from the “left” table, no matter if they have pair in the “right” table or not.

Which is faster joins or subqueries?

The advantage of a join includes that it executes faster. The retrieval time of the query using joins almost always will be faster than that of a subquery. By using joins, you can maximize the calculation burden on the database i.e., instead of multiple queries using one join query.

Why would a left join add rows?

You are getting (possible) multiple rows for each row in your left table because there are multiple matches for the join condition. If you want your total results to have the same number of rows as there is in the left part of the query you need to make sure your join conditions cause a 1-to-1 match.

What is the purpose of LEFT JOIN?

The LEFT JOIN keyword returns all records from the left table (table1), and the matched records from the right table (table2). The result is NULL from the right side, if there is no match.

What does LEFT JOIN mean?

The LEFT JOIN command returns all rows from the left table, and the matching rows from the right table. The result is NULL from the right side, if there is no match.

IS LEFT JOIN same as JOIN?

What is the difference between INNER JOIN and LEFT JOIN. Inner join returns only the matching rows between both the tables, non matching rows are eliminated. Left Join or Left Outer Join returns only the matching rows between both the tables, plus non matching rows from the left table.

Does a foreign key need to be unique?

By the SQL standard, a foreign key must reference either the primary key or a unique key of the parent table. If the primary key has multiple columns, the foreign key must have the same number and order of columns. Any primary key must be unique and non-null.

Can primary key have NULL values?

Primary key constraints A primary key defines the set of columns that uniquely identifies rows in a table. When you create a primary key constraint, none of the columns included in the primary key can have NULL constraints; that is, they must not permit NULL values. NULL values are not allowed.

Can a unique constraint be null?

A Unique Constraint can be created upon a column that can contain NULLs. However, at most, only a single row may ever contain a NULL in that column.

What is a unique constraint violation?

A unique constraint violation occurs when an UPDATE or INSERT statement attempts to insert a record with a key that already exists in the table. A function is attempting to add this sequence, but the value already exists in the table.

What does unique constraint mean?

The UNIQUE constraint ensures that all values in a column are different. Both the UNIQUE and PRIMARY KEY constraints provide a guarantee for uniqueness for a column or set of columns. However, you can have many UNIQUE constraints per table, but only one PRIMARY KEY constraint per table.

Can unique constraint have multiple NULL values?

As per the ANSI, UNIQUE constraint allows multiple NULLs. But in the SQL Server, it allows only one NULL value. With the UNIQUE constraint, you cannot insert multiple NULLs.

Which key accepts multiple NULL values?

Difference Between Primary key & Foreign key

Primary Key	Foreign Key
Helps you to uniquely identify a record in the table.	It is a field in the table that is the primary key of another table.
Primary Key never accept null values.	A foreign key may accept multiple null values.

How do you create a unique key on a column which is having multiple NULL values?

You cannot create a UNIQUE constraint and allow NULLs. You need set a default value of NEWID(). Update the existing values to NEWID() where NULL before creating the UNIQUE constraint.

Which constraint does not allow NULL value and only allows unique values?

PRIMARY KEY constraint differs from the UNIQUE constraint in that; you can create multiple UNIQUE constraints in a table, with the ability to define only one SQL PRIMARY KEY per each table. Another difference is that the UNIQUE constraint allows for one NULL value, but the PRIMARY KEY does not allow NULL values.

Which constraint can be enforced per table?

primary key constraint