#sqlquiz — Public Fediverse posts
Live and recent posts from across the Fediverse tagged #sqlquiz, aggregated by home.social.
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Subquery Returns Multiple Rows In Comparison?!
Using subquery that returns multiple rows in = comparison crashes! SQL doesn't know which row to use. This breaks subqueries! Watch!
#sql #sqltricks #database #sqltutorial #subqueries #multiplerows #sqlquiz #codingchallenge #sqlshorts #sqlbugs #subqueryerrors #sqlwtf
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0.1 + 0.2 In SQL = 0.30000000000000004?!
SQL floating point precision is broken! Adding 0.1 + 0.2 creates a number with precision errors. This breaks financial calculations! Watch!
#sql #sqltricks #database #sqltutorial #floatingpoint #precision #sqlquiz #codingchallenge #sqlshorts #sqlbugs #numericprecision #sqlwtf
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HAVING Filters After GROUP BY?!
HAVING filters GROUPS, WHERE filters ROWS! HAVING runs after aggregation, WHERE runs before. This order matters and will break your logic!
#sql #sqltricks #having #where #groupby #sqlweird #sqlquiz #codingchallenge #sqlshorts #sqlwtf #aggregation #advancedsql
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Window ORDER BY NULLS FIRST - LAST?!
NULLS FIRST and NULLS LAST change window function results! The order of NULLs matters in window functions. This subtle difference will cause bugs!
#sql #sqltricks #windowfunctions #nullsfirst #nullslast #sqlweird #sqlquiz #codingchallenge #sqlshorts #sqlwtf #nullhandling #advancedsql
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Decimal Precision Rounds Numbers?!
DECIMAL precision ROUNDS values! Cast 1.999 to DECIMAL(5,2) and it becomes 2.00. This silent rounding will cause calculation errors!
#sql #sqltricks #decimal #precision #rounding #sqlweird #sqlquiz #codingchallenge #sqlshorts #sqlwtf #datatypes #advancedsql
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COUNT(*) vs COUNT(column) Are DIFFERENT?!
COUNT(*) and COUNT(column) behave completely differently with NULLs! One counts NULLs, one doesn't. This breaks aggregate logic! Watch!
#sql #sqltricks #database #sqltutorial #count #aggregate #sqlquiz #codingchallenge #sqlshorts #sqlbugs #nullhandling #sqlwtf
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JOIN With NULL Keys Returns ZERO Rows?!
JOINing tables with NULL keys returns ZERO rows! NULL = NULL in JOIN is FALSE. This breaks all join logic! Watch!
#sql #sqltricks #database #sqltutorial #join #nullkeys #sqlquiz #codingchallenge #sqlshorts #sqlbugs #joins #sqlwtf
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ROW_NUMBER() OVER (ORDER BY NULL) Does WHAT?!
ROW_NUMBER with ORDER BY NULL creates non-deterministic ordering! All rows get random numbers. This breaks window functions! Watch!
#sql #sqltricks #database #sqltutorial #rownumber #windowfunctions #sqlquiz #codingchallenge #sqlshorts #sqlbugs #ordering #sqlwtf
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LEN('') vs LEN(NULL) vs LEN(' ') Are DIFFERENT?!
LEN of empty string, NULL, and space are all different! Empty = 0, NULL = NULL, Space = 1. This breaks string length logic! Watch!
#sql #sqltricks #database #sqltutorial #len #stringlength #sqlquiz #codingchallenge #sqlshorts #sqlbugs #stringfunctions #sqlwtf
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TRIM with Different Characters?!
TRIM can remove ANY character! Not just spaces. LEADING, TRAILING, or BOTH. This flexible trimming will clean your data in unexpected ways!
#sql #sqltricks #trim #leading #trailing #sqlweird #sqlquiz #codingchallenge #sqlshorts #sqlwtf #stringfunctions #advancedsql
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TRIM with Different Characters?!
TRIM can remove ANY character! Not just spaces. LEADING, TRAILING, or BOTH. This flexible trimming will clean your data in unexpected ways!
#sql #sqltricks #trim #leading #trailing #sqlweird #sqlquiz #codingchallenge #sqlshorts #sqlwtf #stringfunctions #advancedsql
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TRIM with Different Characters?!
TRIM can remove ANY character! Not just spaces. LEADING, TRAILING, or BOTH. This flexible trimming will clean your data in unexpected ways!
#sql #sqltricks #trim #leading #trailing #sqlweird #sqlquiz #codingchallenge #sqlshorts #sqlwtf #stringfunctions #advancedsql
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TRIM with Different Characters?!
TRIM can remove ANY character! Not just spaces. LEADING, TRAILING, or BOTH. This flexible trimming will clean your data in unexpected ways!
#sql #sqltricks #trim #leading #trailing #sqlweird #sqlquiz #codingchallenge #sqlshorts #sqlwtf #stringfunctions #advancedsql
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TRIM with Different Characters?!
TRIM can remove ANY character! Not just spaces. LEADING, TRAILING, or BOTH. This flexible trimming will clean your data in unexpected ways!
#sql #sqltricks #trim #leading #trailing #sqlweird #sqlquiz #codingchallenge #sqlshorts #sqlwtf #stringfunctions #advancedsql
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'10' + 5 In SQL Does WHAT?!
SQL implicit type conversion will shock you! Adding string '10' to number 5 creates something unexpected. This breaks type safety! Watch!
#sql #sqltricks #database #sqltutorial #typeconversion #implicitcast #sqlquiz #codingchallenge #sqlshorts #sqlbugs #typesafety #sqlwtf
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Three-Valued Logic: AND - OR With NULL?!
SQL has THREE truth values: TRUE, FALSE, and UNKNOWN (NULL)! AND/OR with NULL creates logic that breaks everything! Watch!
#sql #sqltricks #database #sqltutorial #threevaluedlogic #null #sqlquiz #codingchallenge #sqlshorts #sqlbugs #booleanlogic #sqlwtf
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Empty String '' vs NULL Are DIFFERENT?!
SQL treats empty strings and NULL completely differently! This hidden difference breaks string logic. Your mind will short-circuit! Watch!
#sql #sqltricks #database #sqltutorial #emptystring #null #sqlquiz #codingchallenge #sqlshorts #sqlbugs #stringcomparison #sqlwtf
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CTE Referenced Multiple Times?!
CTEs can be referenced MULTIPLE times! The same CTE appears in different parts of the query. This reusability will simplify complex queries!
#sql #sqltricks #cte #withclause #multiplereferences #sqlweird #sqlquiz #codingchallenge #sqlshorts #sqlwtf #commontableexpressions #advancedsql
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Recursive CTE Termination Condition?!
Recursive CTEs can loop FOREVER! The termination condition is CRITICAL. One wrong condition and your query hangs. This is how infinite loops happen in SQL!
#sql #sqltricks #recursivecte #withrecursive #termination #sqlweird #sqlquiz #codingchallenge #sqlshorts #sqlwtf #cterecursion #advancedsql
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String Functions With NULL Return NULL?!
LEN, SUBSTRING, and other string functions with NULL return NULL, not error! This breaks string processing logic! Watch the reveal!
#sql #sqltricks #database #sqltutorial #stringfunctions #null #sqlquiz #codingchallenge #sqlshorts #sqlbugs #stringoperations #sqlwtf
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Date Functions With NULL Return NULL?!
DATEADD and DATEDIFF with NULL return NULL instead of error! Date arithmetic with NULL breaks all date logic! Watch now!
#sql #sqltricks #database #sqltutorial #datefunctions #null #sqlquiz #codingchallenge #sqlshorts #sqlbugs #dateoperations #sqlwtf
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Window Frame UNBOUNDED?!
UNBOUNDED PRECEDING means ALL previous rows! UNBOUNDED FOLLOWING means ALL future rows. This creates running totals across the entire window!
#sql #sqltricks #unbounded #preceding #following #sqlweird #sqlquiz #codingchallenge #sqlshorts #sqlwtf #windowframes #advancedsql
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NOT IN With NULL Returns FALSE Always?!
NOT IN with NULL in the list ALWAYS returns FALSE! Even if value is not in list, NULL breaks NOT IN logic completely! Watch!
#sql #sqltricks #database #sqltutorial #notin #null #sqlquiz #codingchallenge #sqlshorts #sqlbugs #setoperations #sqlwtf
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Correlated Subquery With NULL Returns WHAT?!
Correlated subquery with NULL comparison returns something impossible! NULL = NULL in subquery breaks correlation logic! Watch!
#sql #sqltricks #database #sqltutorial #correlatedsubquery #null #sqlquiz #codingchallenge #sqlshorts #sqlbugs #subqueries #sqlwtf
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HAVING With NULL Comparison Breaks Logic!
HAVING clause with NULL comparison returns ZERO rows! HAVING col = NULL never matches. This breaks aggregate filtering! Watch!
#sql #sqltricks #database #sqltutorial #having #null #sqlquiz #codingchallenge #sqlshorts #sqlbugs #aggregatefiltering #sqlwtf