What is a cursor?

What is a cursor?

For the table structure in this instance, see the document "Create a table, insert an id column, and automatically generate an id ".

Use yuyongTest;

Declare @ tot int;

Set @ tot = 0;

Declare @ name nvarchar (50 );

Set @ name = '';

-- Select a column to define the cursor. The cursor serves to traverse the table.

Declare stuName cursor

For

Select Name from student;

-- Open the cursor

Open stuName;

-- Move the cursor down (the first row of data is migrated at the beginning) and assign the current value of the cursor to the variable.

Fetch nextfrom stuName Into @ name;

-- @ Fetch_Status indicates the execution status of the fetch statement.

-- 0 indicates that the FETCH statement is successful.

---1 indicates that the FETCH statement fails or this row is not in the result set.

---2 indicates that the extracted row does not exist.

While (@ Fetch_Status = 0) begin

If (@ name = 'qw ')

Set @ tot = @ tot + 1;

Fetch Next From stuNameInto @ name;

End

-- Close the cursor

Close stuName;

-- Release cursor

Deallocate stuName;

 

Select @ tot;

 

Select COUNT (*) fromstudent where name = 'qw'

Execution result: