通过 SQL，您如何返回 "Persons" 表中记录的数目？
A: SELECT COLUMNS() FROM Persons
B: SELECT COLUMNS(*) FROM Persons
C: SELECT COUNT() FROM Persons
D: SELECT COUNT(*) FROM Persons
A: SELECT COLUMNS() FROM Persons
B: SELECT COLUMNS(*) FROM Persons
C: SELECT COUNT() FROM Persons
D: SELECT COUNT(*) FROM Persons
举一反三
- 通过 SQL，您如何从 "Persons" 表中选取所有的列？ A: SELECT [all] FROM Persons B: SELECT Persons C: SELECT * FROM Persons D: SELECT *.Persons
- 通过 SQL，您如何根据 "FirstName" 列降序地从 "Persons" 表返回所有记录？ A: SELECT * FROM Persons SORT 'FirstName' DESC B: SELECT * FROM Persons ORDER BY FirstName DESC C: SELECT * FROM Persons ORDER FirstName DESC D: SELECT * FROM Persons SORT BY 'FirstName' DESC
- 通过 SQL，您如何从 "Persons" 表中选取 "FirstName" 列的值以 "a" 开头的所有记录？ A: SELECT * FROM Persons WHERE FirstName LIKE 'a%' B: SELECT * FROM Persons WHERE FirstName='a' C: SELECT * FROM Persons WHERE FirstName LIKE '%a' D: SELECT * FROM Persons WHERE FirstName='%a%'
- 通过 SQL，您如何从 "Persons" 表中选取 "FirstName" 列？ A: SELECT Persons.FirstName B: SELECT FirstName FROM Persons C: EXTRACT FirstName FROM Persons
- 通过 SQL，您如何从 "Persons" 表中选取 "FirstName" 列的值等于"Peter" 的所有记录？ A: SELECT [all] FROM Persons WHERE FirstName='Peter' B: SELECT * FROM Persons WHERE FirstName LIKE 'Peter' C: SELECT [all] FROM Persons WHERE FirstName LIKE 'Peter' D: SELECT * FROM Persons WHERE FirstName='Peter'