case-statement

问题 This question already has answers here : Closed 9 years ago . Possible Duplicates: Is "else if" faster than "switch() case"? What is the relative performance difference of if/else versus switch statement in Java? I know that case statements can be implemented with jump tables. Does this make them more efficient than if statements? Is this just micro-optimization that should be avoided? 回答1: I think the main thing is to write the code as clearly as possible. Micro-optimizations like this

问题 I want to create a 64-bit barrel shifter in verilog (rotate right for now). I want to know if there is a way to do it without writing a 65 part case statement? Is there a way to write some simple code such as: Y = {S[i - 1:0], S[63:i]}; I tried the code above in Xilinx and get an error: i is not a constant. Main Question: Is there a way to do this without a huge case statment? 回答1: I've simplified some of the rules for clarity, but here are the details. In the statement Y = {S[i - 1:0], S[63

问题 I'm using a Derived Column Task to change column data using a CASE WHEN statement. However, I need to be able to say.. SQL CODE WOULD BE: CASE WHEN Column01 LIKE '%i%' THEN '0' ELSE '1' END In SSIS Expression Language that would be: [Column01] == "i" ? "0" : "1" (that's for equals i, not, LIKE %i%. Is it possible to use a LIKE operator? 回答1: I believe you'll want to use the FINDSTRING function. FINDSTRING(character_expression, searchstring, occurrence) ... FINDSTRING returns null if either

问题 PostgreSQL 7.4 (Yep upgrading) So in my WHERE condition I have this AND CASE WHEN "substring"(t."FieldID"::text, 0, 3) = '01'::text OR "substring"(t."FieldID"::text, 0, 4) = '123'::text OR "substring"(t."FieldID"::text, 0, 5) = '5555'::text OR "substring"(t."FieldID"::text, 0, 6) = '44444'::text OR "substring"(t."FieldID"::text, 0, 3) = '99'::text THEN 1 ELSE 0 END = 1 Alternate syntax but no change in Cost AND CASE WHEN "substring"(t."FieldID"::text, 0, 3) = '01'::text THEN 1 WHEN "substring

问题 Please forgive my ignorance and poor SQL programming skills but I am normally a basic SQL developer. I need to create a trigger off the insertion of data in one table to insert different data into another table. Within this trigger I need to insert certain data into the new table based upon values within the newly inserted data from the original table. I am totally confused on this. i thought I would be creative and use a case statement within teh Values section but it is not working. Can

问题 I am having a bit of trouble with a query. I want to join tables if a case is met. This the query I'm working with. I'm kind of new to these case statements so any help is greatly appreciated! SELECT conversation.c_id, conversation.user_one, conversation.user_two, users.name, users.lastName FROM `conversation` CASE WHEN conversation.user_one = 1 THEN INNER JOIN `users` ON conversation.two = users.id WHEN conversation.user_two = 1 THEN INNER JOIN `users` ON conversation.user_one = users.id END

问题 Could anyone help me with writing case statements in Informatica PowerCenter Designer? I am fairly new to Informatica, and based on my limited experience I feel case statements aren't supported. There is a decode function with similar functionality, but I am unable to find any good examples on the syntax. I would really appreciate if anyone could give me some specific examples on how to use case statements/decode function in Informatica. Thanks much for your help! 回答1: You're right - there is

问题 Apologies in advance since I feel like I'm probably forgetting/missing something obvious on this one. Here goes; I'm using a case statement in my WHERE clause, the below works fine: WHERE r.[SomeCol] = @SomeColVal AND SomeOtherCol = ( CASE WHEN (@Year = 0 AND @Period = 0) THEN @SomeVal WHEN... ... ELSE @SomeVal END My "issue" is that I want to add an additional OR clause to my ELSE block..something like this: WHERE r.[SomeCol] = @SomeColVal AND SomeOtherCol = ( CASE WHEN (@Year = 0 AND

问题 Folks, Recently started learning C. Stuck at a point. Its about working of switch-case statement. Here's the code : #include<stdio.h> int main() { int i=4; switch(i) { default : printf("%s","Default"); case 0: printf("%s","Case 0"); case 1: printf("%s","Case 1"); case 2: printf("%s","Case 2"); return 0; } } I personally think, " Default " should be printed, as it doesn't match with any of case value. But when I run the code in Turbo C, what I observed was this : Default Case 0 Case 1 Case 2

问题 Trying to figure out a way to return in a case statement. For example, if you run this.... while : do clear cat<<-EOF ====================== Foo Bar Doo Dah Setup ====================== (1) Foo (2) Bar (q) Quit ---------------------- EOF read case $REPLY in "1") foo="foo" ;; "2") bar="bar" ;; "q") break ;; * ) echo "Invalid Option" esac sleep .5 clear cat<<-EOF ====================== Foo Bar Doo Dah Setup ====================== (1) Doo (2) Dah (q) Quit ---------------------- EOF read case