db2 coalesce

In the ETL project often encounter such a situation:A column in the target table originates from a different source data table A,b,c. If no valid data in A is taken from B, if none in B is taken from C, then set to null if none is in C.In situations like this, sometimes the first thought is the case and then else end, which can solve the problem, but it's still more complicated and error-prone, especially when someone looks at the SQL you're writing.So is there a better way?That's the

Coalesce and coalesce There is such a demand. There are several contacts in the community. If there is a power outage, first notify contact 1. If not, then notify contact 2; otherwise, notify contact 3. Create table test (Id number,Name varchar2 (20 ),Contact_phone1 varchar2 (20 ),Contact_phone2 varchar2 (20 ),Contact_phone3 varchar2 (20 ),Contact_phone4 varchar2 (20));Insert into test values (1, 'cell 1',

Performance Comparison Between ISNULL and COALESCE in the paging mode of SQL Server, isnullcoalesce Preface In the previous section, we explained the data type and several notes in the string. In this section, we will continue to talk about the number of string lines, other content and interspersed content, short content, and in-depth explanation. (For details, see "Data Types in SQL Server".) Paging Mode In SQL 2005 or SQL 2008, we use ROW_NUMBER Win

, the use of offset-fetch to achieve it is a blast. Coalesce Compare to ISNULL In the previous section we talked about string functions, which omitted a string function called COALESCE, which is available on the SQL 2008+, and there are several other similar handles to string functions, which we'll look at together. It is defined by MSDN to evaluate the variable in order and return the current value of th

the SQL version to 2005, the use of offset-fetch filter filtering, it is based on SQL 2011. The above we take data from 31 to 40, if implemented with Offset-fetch, we can see that the function literally means to know how much data is skipped and how much data to crawl, so we need to skip the previous 30 data, we need to take the next 10 data.Ten 3 * fromsales.customersorder to CustID* @PageSize rowsfetch NEXT ROWS only GOIf the SQL version requirements are not low, the use of offset-fetch to

SQL Server COALESCE functions detailed Many people know the IsNull function, but few people know the COALESCE function, people will inadvertently use the COALESCE function, and found that it is more powerful than isnull, in fact, so far, this function is indeed very useful, this article mainly explains some of the basic uses: first look at the brief definition

altThe method allows us to recover from a nothing with a default maybe, but sometimes our recovery efforts might need t o Enlist some logic to recover properly. In this lesson, we'll see how we can use the method on the maybe to recover from a nothing by coalesce calling a function. When one would like option to a Maybe but would like to remain within a Maybe type, coalesce can be used.

Reprint Address: http://blog.csdn.net/dba_huangzj/article/details/8300784#Directory First look at the brief definition of Books Online Grammar Here are a few more useful examples First take a look at how this function is used on MSDN COALESCE function returns a value that is not NULL in a parameter, such as Then take a look at applying the function to pivot. The following statement runs on the AdventureWorks databa

Tags: technical SQL function too share span current time fun tar strongHere are a few more useful examples: First, take a look at the use of this function from MSDN, the COALESCE function (hereinafter referred to as the function), and return a non-null value for a parameter. Such as: SELECT COALESCE (null, null, GETDATE ()) Since all two parameters are null, the value of the GETDATE ()

The difference between ALTER INDEX COALESCE and ALTER INDEX rebuild:Alter index COALESCE is the leaf block that merges the same branch.and ALTER index rebuild is to re-establish a indexes, generally need twice times the size of the index space . and needs sorting. Add: It says that "coalesce index" consumes less resources than "rebuild index". In my tests,

Tags: blog HTTP Io ar use for SP strong data Turn: http://blog.csdn.net/dba_huangzj/article/details/8300784 Many people know the isnull function, but few know the coalesce function. People will accidentally use the coalesce function and find it more powerful than isnull. In fact, this function has been very useful so far, this article mainly describes some basic usage: First, let's take a look at the

People often encounter coalesce functions, and most of them regard them as a more effective form of isnull. In fact, I found that it is a very useful function, but there are only a few documents. In this article, I will show you the basic usage of coalesce and some features you may have never seen before. Let's start with the use of coalesce with documented rec

Database Application Software often saves multiple and related entity information in the same table. For example, the purchased parts and locally produced parts are both parts, and the managers and workers are employees. Although multiple entity types are slightly different in data storage, they have many similarities, therefore, we usually use one table instead of two tables. Processing such a table usually means performing a condition test on each row to check which object type is being proc

Tips for using coalesce () in mysql Coalesce () Explanation The first non-empty expression in the return parameter (from left to right, and so on); Tips for using coalesce () in mysql Example A, B, and c variables. Select coalesce (null, 2, 3); // Return 2 Select coalesce