Question
In SQL, which type of JOIN will return all rows from the
left table and the matching rows from the right table, filling with NULLs where there is no match?Solution
A LEFT JOIN in SQL returns all records from the left table (the first table specified in the query) and the matched records from the right table. If there is no match, the result will contain NULL values in columns from the right table. This join type is particularly useful in scenarios where you need to keep all data from the primary table, even if corresponding records do not exist in the related table. It is commonly used when performing analyses requiring comprehensive data from one table while optionally pulling related data from another. The other options are incorrect because: • Option 1 (INNER JOIN) only returns rows with matching values in both tables. • Option 3 (RIGHT JOIN) returns all rows from the right table, not the left. • Option 4 (FULL JOIN) includes all matching and non-matching rows from both tables. • Option 5 (CROSS JOIN) returns the Cartesian product without any filtering on matching keys.
In the question below there are three statements followed by two conclusions I and II. You have to take the three given statements to be true even if t...
Statements:
A few parrots are hens.
No parrot is bird.
All bird are sparrows.
Conclusions:
I: Some hens are not b...
In the questions given below there are three statements followed by three conclusions I, II and III. You have to take the three given statements to be...
have to take the three given statements to be true even if they seem to be at variance from commonly known facts and then decide which of the given co...
In the question below there are three statements followed by two conclusions I and II. You have to take the three given statements to be true even if t...
Statements: No wire is a line.
                          All lines are modems.
Conclusions: I. Some modem...
Read the given statements and conclusions carefully. Assuming that the information given in me statements is true. Even if it appears to be at varianc...
Statements:Â Â Â Â Â Â Some pen are pencil.
All pencil are book.
Conclusions:Â Â Â Â Â Â I. Some pen are book.
II. Some book are ...
Statements: All males are females.
All females are men.
No man is a woman.
All women are Girl...
Statements:
Some pulses are grams.
No pulse is a bean.
All grams are wheat.
Conclusions:
I. All wheat being pulses ...