1) What is SQL? 2) What is a primary key? 3) What is a constraint? 4) Which operator is used in a query for pattern matching?
1) SQL stands for Structured Query Language, and it is used to communicate with the Database. It is a standard language used to perform tasks such as retrieval, updates, insertion, and deletion of data from a database. 2) A primary key is a combination of fields which uniquely specify a row. This is a special kind of unique key, and it has an implicit NOT NULL constraint. It means Primary key values cannot be NULL. 3) The constraint can be used to specify the limit on the data type of table. The constraint can be specified while creating or altering the table statement. A sample of constraint is. NOT NULL. CHECK. DEFAULT. UNIQUE. PRIMARY KEY. FOREIGN KEY. 4) LIKE operator is used for pattern matching, and it can be used as -. % – Matches zero or more characters. _(Underscore) – Matching exactly one character. Example -. Select * from Student where student name like ‘a%’ Select * from Student where student name like ‘ami_’
Change the following sentences from the active to the passive voice. Changez les phrases suivante de la voix active à la voix passive. Active voice David fait le ménage. (David is doing the housework.) Mes amis aiment ma mère. (My friends love my mother.)
When the verb expresses an action, the agent is introduced by the preposition 'par': Lorsque le verbe exprime une action, le sujet est introduit par la préposition 'par': Passive voice Le ménage est fait par David. (The housework is done by David.) When the verb expresses a state of being, the agent is either introduced by de or left out entirely: Lorsque le verbe exprime un état d'être, l'agent est introduit par 'de' ou totalement exclu: Passive voice Ma mère est aimée de mes amis. (My mother is loved by my friends.)
You are given the following equation: x-8=15. Solve for x.
Re-write the equation: x-8=15 Add 8 on both sides of the equation to solve: x-8+8=15+8 Write the final answer which is the value of x: x=23. Another way of solving this would be to move -8 to the other side of the equation. By doing so, the integer's sign will change and be therefore a positive number: x-8=15 x=15+8 x=23