Basic Database interview and database interview

Basic Database interview and database interview

1. Update table data (table_ B is updated through table_A)

The structure of tables A and B is as follows:

Create table [dbo]. [Table_A] ([Id] [varchar] (36) not null, [Name] [nvarchar] (50) NULL) ON [PRIMARY]

Create table [dbo]. [Table_ B] ([Id] [varchar] (36) NOT NULL, [Name] [varchar] (50) NULL) ON [PRIMARY]

The data before the test is as follows:

Update statement:

Update Table_ B set Table_ B .Name = A. Name from Table_ B as B, Table_A as Awhere B. Id = A. Id

The result is as follows:

Note:

SQL is not frequently written, and many things are forgotten. It seems that your data knowledge is still too poor. mark it here.

2. Comparison of clustered indexes and non-clustered indexes (to be continued)

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