sql if count 0 then

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How big is the difference between count (*) and COUNT (1)?

The number of records in the database table is: Sql> Select COUNT (*) from table_name t; COUNT (*)----------6873 1, using the statistical results of COUNT (*): Sql> alter session Set Nls_language = "American"; Session altered. Sql> set timing on;Sql>

How Does Oracle SQL display queries with group by aggregation result count 0?

How to display 0 in conditional [Group by] Report in count () SQL query Challenge:Let me assume this: we have two tables, one is regions table with all region information (east, west, etc .) and we have another table with sales information. now, we

In MySQL, COUNT (1) is compared to count (*)

SQL tuning is primarily about reducing the number of consistent gets and physical reads. COUNT (1) is compared with COUNT (*): If your datasheet does not have a primary key, then count (1) is faster than COUNT (*)If you have a primary key, the

Case of SQL when and then usage (for categorical statistics)

Case has two formats. Simple case function and case search function.--Simple case function when ' 1 ' then ' Male ' when ' 2 ' Then ' Women ' Else ' other ' end--case search function case when sex = ' 1 ' Then ' Man ' when sex = ' 2 '

Nested transactions in SQL Server use--transaction count indicates a mismatch between the number of BEGIN and COMMIT statements--The underlying problem

Turn from: Nested transactions in SQL Server use--transaction count indicates a mismatch between the number of BEGIN and COMMIT statements--The underlying problemProblem:1. System.Data.SqlClient.SqlException (0x80131904): The transaction count after

[SQL] how to display the result with Count () 0 in select statements containing group

1. Problem In the following exampletable table, find the number of records with each type (categoryid) meeting the flag value of 1. ID Flag Categoryid 1 1 1 2 1 1 3

Replace count query with sum in DB2

In DB2, the sum function used to replace the count query is to calculate and sum the column values. The www.2cto.com count function accumulates the columns that meet the conditions and adds one when the conditions are met. The count function is

[Oracle] "The table has data, but the result of select COUNT (*) is 0" solution to the problem

First, the questionToday there is a magical problem-there is data in the table, but the result of select COUNT (*) is 0.The initial manifestation of the problem is that the query report has no paging.At first, I thought it was a Java-side problem.

Try to do it every day. SQL (ii) Count sum case-then-group by

1.Select SUM (case if a.[status]=0 then 1 ELSE 0 End) as A1,SUM (case A.[status] When 1 then 1 ELSE 0 end) as A2,SUM (case A.[status] When 2 then 1 ELSE 0 end) as A3,A.userid,c.trainidFrom Coursewarelogmiddle A join Lessondetail BOn

SQL SQL Server (verbose) SQL statement optimization _mssql

MS SQL Server Query optimization methodThere are many reasons for the slow speed of queries, which are common1, no indexes, or no indexes (this is the most common problem with query slowness, is the flaw in programming)2, I/o throughput is small,

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