Example decode oracle12/5/2023 Oracle documentation notes the following syntax for decode:įilled with valuable information on Oracle SQL Tuning. By using decode to change the ranges to a binary number, we can then use the sum built-in function to count the number of values within a specified range. The power of these functions become apparent when combined with the decode built-in function. The case statement is an easier form of the decode statement. Oracle added the case function to SQL starting in Oracle9i to simplify this type of data transformation. Once we have converted the column to a 0-1 numeric value, we pass the entire clause to the sum function, and add-up the numbers.Īs we can see, the decode function is convoluted and hard to write. This is a very important SQL statement because it demonstrates the nesting of BIFs and the use of decode for counting values. Sum(decode(book_type,'miscellaneous',1,0)) miscellaneous, Sum(decode(book_type,'management',1,0)) management, Sum(decode(book_type,'fiction',1,0)) fiction, Sum(decode(book_type,'computer',1,0)) computer, Initcap(substr(pub_name,1,20)) publisher_name, Here is the SQL to create this report in your pubs database: The default value tells decode what to display if a column values is not in the paired list. At the end of the decode statement we find a default value. Note that Oracle decode starts by specifying the column name, followed by set of matched-pairs of transformation values. Here is how we do this with the decode function: When we run SQL queries, we want to transform these values into North, South, East and West. For example, say we have a column named REGION, with values of N, S, W and E. The Oracle decode statement was developed to allow us to transform data values at retrieval time. Let's take a look at how the decode statement works. Oracle started with the decode statement and later refined it in Oracle9i, morphing it into the case statement. One of the most amazing features of the case the Oracle decode statements is that they allow us to create an index on data column values that do not exist in the database. The Oracle decode and case functions are used within the Oracle database to transform data values for one value to another. On web.oid_web_activity_fct = o.The most powerful of all of the BIFs are the Oracle decode and Oracle case function. On WEB.OID_WEB_ACTIVITY_FCT = C.OID_SILVERPOP_CLICK SUM(case when WEB.EVENT_TYPE in(5,6,7,8)then WEB.ACTIVITY_COUNT END) +o.count(*) as Totalįrom GMMI_AIR.WEB_ACTIVITY_FCT WEB join GMMI_AIR.SILVERPOP_CLICK C Sum(case when c.when_clicked is not null then c.count(*))as clickcount, SUM(case when o.WHEN_OPENED is not null then o.COUNT(*))as OPENCOUNT, -In this table they don’t have seprate field named ’Actitvity_count SUM(DECODE(WEB.EVENT_TYPE,7,WEB.ACTIVITY_COUNT,0)) as DISCUSSIONVIEW, SUM(DECODE(WEB.EVENT_TYPE,6,WEB.ACTIVITY_COUNT,0)) AS DISCUSSIONSTART , SUM(DECODE(WEB.EVENT_TYPE,5,WEB.ACTIVITY_COUNT,0)) AS DISCUSSIONCOMMENT , I also like case statements as I have been using Sql server all the time, but in this job they use ORACLE and part of the query was already written, I had to add few more columns where I tried something like this! I am really confused as I can do sum of one activity in decode but how do I write statement where in one decode statement it's adding up more than one activity?Īnd also want to ask that if some event is coming from other table can I still use the joined fields from other tables in my decode statement? I am confused if I can do something like this? Most of the events are coming from one table, but in one column I have to show total of( open+view+print+register etc) and this all should come as one column as engagement _count along with other individual counts. SUM(DECODE(WEB.EVENT_TYPE,35,WEB.ACTIVITY_COUNT,0)) AS Cpn_Aprt SUM(DECODE(EVENT_TYPE,33,WEB.ACTIVITY_COUNT,0)) AS Cpnw SUM(DECODE(EVENT_TYPE,34,WEB.ACTIVITY_COUNT,0)) AS Cpn_Red , SUM(DECODE(EVENT_TYPE,5,WEB.ACTIVITY_COUNT,0)) AS DISCUSSION, SUM(DECODE(EVENT_TYPE,2,WEB.ACTIVITY_COUNT,0)) AS BLOG I am trying to provide counts of different activities from one table, however few counts will come from other table and in the same query I also have to provide sum of 5 activities in one column.
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