Structured Query Language (sql)
Akopọ
A database with a million records is useless unless you can ask it a question and get the four rows you actually wanted. The language for asking is SQL, and its central idea is unusual for a programming language: you describe what you want rather than how to find it. You do not write a loop over a million records. You say which fields, from which tables, matching which condition, and the database works out the rest.
This lesson covers the commands the specification names. You will learn to retrieve data with SELECT, FROM and WHERE, including queries that draw on two tables at once; to add a record with INSERT INTO; and to edit and delete data with UPDATE and DELETE FROM. You will also learn the single most consequential detail in the whole topic, which is what happens to an UPDATE or a DELETE that is missing its WHERE clause.
Awọn Afojusun
- Be able to use SQL to retrieve data from a relational database, using the commands:
- SELECT
- FROM
- WHERE. Be able to use SQL to insert data into a relational database using INSERT INTO. Be able to use the SQL commands UPDATE and DELETE FROM to edit and delete data in a database.
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Ìdánwò Ẹ̀kọ́
Oriire fun ipari ẹkọ lori Structured Query Language (sql). Ni bayi ti o ti ṣawari naa awọn imọran bọtini ati awọn imọran, o to akoko lati fi imọ rẹ si idanwo. Ẹka yii nfunni ni ọpọlọpọ awọn adaṣe awọn ibeere ti a ṣe lati fun oye rẹ lokun ati ṣe iranlọwọ fun ọ lati ṣe iwọn oye ohun elo naa.
Iwọ yoo pade adalu awọn iru ibeere, pẹlu awọn ibeere olumulo pupọ, awọn ibeere idahun kukuru, ati awọn ibeere iwe kikọ. Gbogbo ibeere kọọkan ni a ṣe pẹlu iṣaro lati ṣe ayẹwo awọn ẹya oriṣiriṣi ti imọ rẹ ati awọn ogbon ironu pataki.
Lo ise abala yii gege bi anfaani lati mu oye re lori koko-ọrọ naa lagbara ati lati ṣe idanimọ eyikeyi agbegbe ti o le nilo afikun ikẹkọ. Maṣe jẹ ki awọn italaya eyikeyi ti o ba pade da ọ lójú; dipo, wo wọn gẹgẹ bi awọn anfaani fun idagbasoke ati ilọsiwaju.
- Which SQL clause states which records a query should return? A. SELECT B. FROM C. WHERE D. INSERT INTO Answer: C
- Which query correctly finds the names of all cats and all birds in a table called Pet? A. SELECT Name FROM Pet WHERE TypeOfAnimal = 'Cat' AND TypeOfAnimal = 'Bird' B. SELECT Name FROM Pet WHERE TypeOfAnimal = 'Cat' OR TypeOfAnimal = 'Bird' C. SELECT Name FROM Pet WHERE TypeOfAnimal = Cat OR Bird D. SELECT Name FROM Pet WHERE TypeOfAnimal = 'Cat' OR 'Bird' Answer: B
- What does the statement DELETE FROM Booking do if it has no WHERE clause? A. Nothing, because a WHERE clause is required B. It deletes the first record only C. It deletes every record in the Booking table D. It deletes the Booking table's field names Answer: C
- Which command is used to change the value already stored in a field? A. SELECT B. INSERT INTO C. UPDATE D. DELETE FROM Answer: C
- In a query drawing on two tables, what is the purpose of a condition such as Pet.PetID = Appointment.PetID? A. It sorts the results into order B. It matches each record in one table with the correct record in the other C. It deletes records that appear in both tables D. It renames a field Answer: B
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Ṣe o fẹ ṣe adaṣe awọn ibeere idanwo adaṣe nipa Structured Query Language (sql)? Ṣe igbasilẹ ohun elo Green Bridge CBT lati wọle si awọn ibeere idanwo adaṣe ati awọn ayẹwo adaṣe kikun fun koko-ọrọ yii.
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