compare two columns in sql

1. Create a table:CREATE TABLE Student Information(School Number varchar (+) IDENTITY (PRIMARY KEY),Name varchar (8) UNIQUE not NULL,Class number varchar (+) REFERENCES ' class information ',grade int NULL,Gender varchar (2) CHECK (Sex in (' Male ', ' female ')),National varchar (a) DEFAULT ' unknown to the living nation ',Native Place varchar (50))2. Modify the table:A. Renaming A table:EXEC sp_rename ' oldname ', ' newname 'B. Modify Column Properties:ALTER TABLE Student InformationALTER COLU

Cross tabulation is frequently used. Dynamic columns can be generated using dynamic SQL !. Original table format: ClassCallDateCallCount12005-8-84012005-8-7622005-8-87732005-8-93332005-8-8932005-8-721 according to the value of Class, respectively according to the date CallC original table format: Class CallDate CallCount 1 2005-8-8 40 1 2005-8-7 6 2 2005-8-8 77 3 2005-8-9 33 3 2005-8-8 9 3 2005-8-7 21 CallC

: This article mainly introduces the SQL statement for the same table. PHP queries the sum of two columns of data and then outputs the results. if you are interested in the PHP Tutorial, you can refer to it. // Calculate the total order quantity $query_num = "SELECT SUM(order_num) from hcf_order_db where order_id = XXX";$arr_qn = mysqli_query($dbc,$query_num);list($sum)=mysqli_fetch_row($arr_qn); // Calcul

You can't add that!Some data is null, null+ any value =nullNot if you say that.Update Set HY_MYGGCYSWCQKB. Sj_by_sr=hy_myggcyswcqkb. Sj_by_sr+hy_myggcyswcqkb. Sj_by_sr_tz-hy_myggcyswcqkb. SJ_BY_SR_TJ;If there is a column that is not NULL, the result of the addition is null.Normal, yes.SELECT Total + Money From TableYou can do it.But:Some of the data is empty and needs to be based on different databases, with unused functionsThat is, if the data is empty, then it is calculated according to

Strictly speaking, having does not require a child table, but having no child table has no practical significance. If you only need a table, then you can use the WHERE clause to achieve all of your goals. For practice, having presupposes at least two tables and an aggregate function based on the second table. Here's a simple example: you want a customer list with a total order of more than 25000 dollars. You need to properly connect the three tables: Customer, SalesOrderHeader and SalesOrderDet

Strictly speaking, having does not require a child table, but having no child table has no practical significance. If you only need a table, then you can use the WHERE clause to achieve all of your goals. For practice, having presupposes at least two tables and an aggregate function based on the second table. Here's a simple example: you want a customer list with a total order of more than 25000 dollars. You need to properly connect the three tables: Customer, SalesOrderHeader and SalesOrderDet

Requirements: query the summary of the graduation design carried by each teacher. The graduation design students are divided into undergraduate, specialist, out-of-hospital, and in-hospital students. The results are as follows: Instructor name: Total number of out-of-hospital Undergraduate Courses Related tables include: Student table (including student level), teacher table (Instructor name), student subject table (student-teacher correspondence and out-of-hospital information ). The

The data table contains a column of data, as shown in 1: Figure 1 data table Now we need to divide the data in this column into three columns. The SQL code is as follows: 1, SelectMax (case when F1 % 3 = 1 then F1 else 0 end),Max (case when F1 % 3 = 2 then F1 else 0 end) B,Max (case when F1 % 3 = 0 then F1 else 0 end) cFrom hlr151Group by (F1-1)/3 Effect: 2, SelectC1 = A. F1, C2 = B. F1, C3 = C.

Since MS SQL Server 2005, Microsoft has introduced batch and unbatch to implement row-and-column conversion, which greatly facilitates data storage and presentation. Today, we will analyze these two keywords and explain how to store and present data with examples.For example, there is a table in the Student Course Selection and score system, which stores the students' course scores. We cannot predict the number of courses. Therefore, the general table

The following two tables have the same structure. use SQL to find columns with different values. Student_1 NAME AGE SCORE Peter 26 100 Jack 25 96 Daniel 26 48 Bark 21 69 Student_2 NAME AGE SCORE Peter 26 89 Jack 25 96 Daniel 26 48 Bark 21 69 Metho

SQL Max such aggregate functions can only be for the same column of n row operations, if the N column operations, generally use case statements to judge, if the column is relatively easy to write, the list of more trouble. --------------------------------------------------------------------------------/* Test name: Using XML Find aggregations between arbitrary columns Test functionality: Make min, Max, SU

Tags: val master charindex sel technology string here desc des Raw data that needs to be stitched together into one line SELECT * FROM (select d.*, (select count ([Keyword]) from [dragonguoshi].[ DBO]. [Articleinfo]where Keyword like '% ' +d.keyword+ '% ' and [articlecreatedate]> ' 2018-06-10 ') as Num from (SELECT DISTINCT ( Keyword) from (select SUBSTRING (Keyword,number,charindex (', ', keyword+ ', ', number)-number) as Keyword from (select Stuff (select ', ' +[keyword] from (select [Keywor

Query each student's (name, language, maths, English, score) for the columnThe table structure is as follows:Student: Student TableGrade score Table:The following effect is queried:SQL is as follows:Select s.name,a.* from Student S, (select Sid,max (case kemu "language ' then Chengji ELSE 0 END) ' Language ', max (case kemu when ' math ') Then Chengji else 0 end) ' Math ', max (case Kemu when ' English ' then Chengji ELSE 0 end) ' English ' from grade GROUP by Sid Awhere S.id = A.sid　　

Label:Let's take a look at the example below: Table tables Field 1 Field 2 ID Name 1 A 2 b 3 C 4 C 5 b The library structure is probably like this, this is just a simple example, the actual situation will be much more complex. For example, if I want to use a single statement to find all the data that name does not repeat, then you must Use distinct to remove redundant duplicate records. The results from the select DISTINCT name from table are: ---------- Name AC It seems to be working, but what

: Table_source Pivot (aggregate function (Value_column) pivot_column for (columnlist)) A little explanation: Table_source: Is the table we want to convert. Pivot_column: Is the column name for row to column. Value_column: Is the value of the column after the conversion. Columnlist is the column to be generated. This is also the case with pivot, which can be used to write the same result: Select Studentname, [Chinese] Chinese, [math] math, [English] 中文版 from (SELECT * from