PostgreSQL CASEs can have multiple conditions. There are a handful of entries in the table where the name of country and capital is the same. You can add this to your previously constructed CASE - SELECT name, continent, indep_year, CASE WHEN (indep_year < 1900) AND (countries.name = co...
WHEN value2 THEN result2 ... ELSE default_result END; Searched CASE Unlike the Simple CASE that evaluates a single expression against multiple values, the Searched CASE evaluates multiple conditions. Its structure is: CASE WHEN condition1 THEN result1 WHEN condition2 THEN result2 ... ELSE defau...
exists already.*/voidsmgrreleaserellocator(RelFileLocatorBackendrlocator){SMgrRelationreln;/* Nothing to do if hashtable not set up */if(SMgrRelationHash==NULL)return;reln=(SMgrRelation)hash_search(SMgrRelationHash,&rlocator,HASH_FIND,NULL);if(reln!=NULL)smgrrelease(reln);}/** smgrreleaseall(...
CASE condition WHEN condition value THEN statement ELSE additional statement; Example We can use CASE to evaluate multiple conditions for a single variable, “job_id.” If “job_id” is “ACCOUNT,” the salary increase is 10%; if “job_id” is “IT_PROG,” the salary...
*/ StaticAssertDecl(THRESHOLD_SUBTRANS_CLOG_OPT <= PGPROC_MAX_CACHED_SUBXIDS, "group clog threshold less than PGPROC cached subxids"); /* * When there is contention on XactSLRULock, we try to group multiple * updates; a single leader process will perform transaction status * updates ...
*/ oldContext = MemoryContextSwitchTo(econtext->ecxt_per_tuple_memory); /* * Evaluate the qual conditions one at a time. If we find a FALSE result, * we can stop evaluating and return FALSE --- the AND result must be * FALSE. Also, if we find a NULL result when resultForNull ...
If any of the upper 25/17 bits are not zero, the code point is broken into multiple 1-byte (UTF-8) or 2-byte (UTF-16) sequences based on someclever rules, One of the very nice features of Unicode is that any code point where the upper 25 bits are zero is exactly the same as...
Having – apply conditions to groups, which allow you to filter groups. Section 5. Set Operations Union – combine result sets of multiple queries into a single result set. Intersect –combine the result sets of two or more queries and return a single result set containing rows that appe...
once, rather than assume they can read it multiple times and get the same answer each time. (Use volatile-qualified pointers when doing this, to ensure that the C compiler does exactly what you tell it to.) Another important activity that uses the shared ProcArray is GetOldestXmin, ...
Each Plan node may have expression trees associated with it, to represent its target list, qualification conditions, etc. These trees are also read-only to the executor, but the executor state for expression evaluation does not mirror the Plan expression’s tree shape, as explained below. Rather...