无法将if then逻辑实现到sql代码

Question

想要将SAS代码更改为SQL，但不知道应该遵循哪种方法，但我尝试了case when，它给了我错误。

SAS代码：

length list_of_Fields $400.;
list_of_Fields = "";

if missing(column_a)        eq 1 then do; if calc_of_count <= limit_of_Count then list_of_Fields = catx(" ;", calculation_of_columnName, "Company1"); calc_of_count + 1; end;
if missing(column_b)        eq 1 then do; if calc_of_count <= limit_of_Count then list_of_Fields = catx(" ;", calculation_of_columnName, "Company2"); calc_of_count + 1; end;


if list_of_Fields eg "" then list_of_Fields = &strNone

SQL代码：

case 
    when column_a is null then case when calc_of_count <= limit_of_Count then ist_of_Fields = catx(" ;", calculation_of_columnName, "Company1") 
    when column_b is null then case when calc_of_count <= limit_of_Count then list_of_Fields = catx(" ;", calculation_of_columnName, "Company2") 

不幸的是没能完成，你能帮我找一下路吗？

Answer 1

您可以通过以下方式完成此操作：

CASE 
    WHEN (column_a is null AND calc_of_count <= limit_of_Count) THEN ist_of_Fields = CONCAT(" ;", calculation_of_columnName, "Company1") 
    WHEN (column_b is null AND calc_of_count <= limit_of_Count) THEN list_of_Fields = CONCAT(" ;", calculation_of_columnName, "Company2") 
    ELSE list_of_Fields = &strNone
END

您也可以尝试使用以下格式的IF子句：

IF(condn, TRUE_STATEMENT, FALSE_STATEMENT);