sql count distinct values

SQL Multiple primary key tables, when the inserted data is duplicated, are prompted to violate the primary KEY constraint that cannot be inserted by the error. So, how do I find duplicate values for the inserted data? Workaround: Use Group bySuppose there is a table #a , there are saleid,vendorid,comid,price,saleprice,quantity and other fields. The primary key is: Saleid,vendorid,comid three of them. Assu

In Pb, the stored process is saved using SQL statements (bringing numbers and returned values) /// Declare the stored procedure:Create procedure proc_pslx (@ name varchar (2), @ count integer output)As Select @ COUNT = count (*) from wo_info where whs_name = @ name; Go

Label:Mesh: Zdjz_dis The NAME field has a duplicate value, delete the duplicate value deleted * from zdjz_dis WHERE name in (select Name from Zdjz_dis GROUP by NAME has count (NAME) >1); The above procedure will remove all the same values, including the one you want, and delete the delete * from Zdjz_dis WHERE ID in (select min (ID) from Zdjz_dis Group) as long as you repeat by NAME has

SQL uses three-valued predicate logic, so the result returned by a logical expression can be true, false, or unknown, and returning true in the three-value logic is not exactly the same as not returning false.SQL handling of query filtering conditions: Accept Ture deny false and unknownSQL handling of CHECK constraints: Accept FALSE deny TRUE and UNKnown the subtlety of unknown is when it is reversed results are still unknown ,

the comments below)--correct wordingSELECT * fromDbo. Table_a asaWHEREa.ID not inch(SELECTb.id fromDbo. Table_b asbWHEREb.ID is not NULL)--exclude null values to participate in operator comparisons --suggested modifications to the associated query method--correct wording 1SELECT * fromDbo. Table_a asaWHERE not EXISTS(SELECT * fromDbo. Table_b asbWHEREa.ID=b.id)--correct wording 2SELECT * fromDbo. Table

1: Normal SQL statements can be executed with execEg:select * from TableNameExec (' select * from TableName ')sp_executesql n ' select * from TableName '--please note that the string must be added N before2: Field name, table name, database name, etc. as variables, you must use dynamic SQLegDECLARE @fname varchar(20)Set @fname = ' [name] 'Select @fname from sysobjects--errorExec (' select ' + @fname + ' from sysobjects ')--please note that a space is

Tags: SQL Server lookup duplicate values temporary tableA string of "1;2;1;1;1".Excuse me:How to implement the following features in SQL Server:1. Determine if there are duplicate numbers in the stringIf there are duplicate numbers, an error message is returnedIf there are no duplicate numbers, the return is correct. Idea: Splitting a string, depositing a substr

In MySQL:[SQL] Viewplaincopyprint?--single-row stitching, first find a row, plus a comma, and then the next line of stitching isolatedSelectGroup_concat (E.support) fromENGINES EwhereE.xainch('YES','NO') --The results are as follows: Yes,yes,yes,yes,yes,yes,default,yes --replace the "," in the result of the query with the "* *" numberSelect REPLACE(Group_concat (E.support),',','**') fromENGINES EwhereE.xainch('YES','NO') --The results are as fo

Original: "SQL" finds tables with unequal row count and self-increment identity value (that is, there are missing rows)Environment:MSSQL ENT 2k8 R2principle: traverse all user tables with self-increment columns, get the number of rows per table and write to the temporary table using the sp_spaceused procedure, and then use the Ident_current function to get the maximum identification value of the table, comp

Tags: analyze different nbsp cas rom pre same count spanRequirements: There are two or three columns in a table, respectively, "Cargo name", "Arrival Time", "Shipping Time", "Storage Days", the name of the goods and two kinds of "fish", "meat", now the demand is such: if the meat purchase time and the fish shipped the same time the fish show the actual "storage Days", otherwise " Storage Days "is 0, the meat" storage days "normal display. Analysis: 1,

Requirements Description:1, in the project need to calculate the duration of a link and the number of times of the link.2, the requirement duration in minutes to display, and count the number of times.How to resolve:It is determined by calculating the difference in the number of seconds between the start time and the end time of a link.Code section:Description: The database uses MySQL, and the persistence layer framework uses MyBatis.The code is as fo