#sqltutorial — Public Fediverse posts
Live and recent posts from across the Fediverse tagged #sqltutorial, 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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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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'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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10 % 0 Modulo By Zero Returns WHAT?!
Modulo by zero in SQL doesn't always crash! Some databases return NULL, others error. This breaks math operations! Watch the chaos!
#sql #sqltricks #database #sqltutorial #modulo #divisionbyzero #sqlquiz #codingchallenge #sqlshorts #sqlbugs #mathoperations #sqlwtf
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NULL IN (1,2,3) Is NOT What You Think!
Your brain will explode! Checking if NULL is IN a list returns something that makes NO sense. This breaks every query! Watch the chaos!
#sql #sqltricks #database #sqltutorial #nullin #sqlquiz #codingchallenge #sqlshorts #sqlbugs #inclause #sqlwtf #threevaluedlogic
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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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GROUP BY NULLs Are Treated As ONE?!
GROUP BY treats all NULLs as the same group! Multiple NULL rows get grouped together. This breaks grouping logic! Watch now!
#sql #sqltricks #database #sqltutorial #groupby #nullhandling #sqlquiz #codingchallenge #sqlshorts #sqlbugs #grouping #sqlwtf
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NULL = NULL Is FALSE In SQL?!
STOP SCROLLING! Comparing NULL to NULL in SQL returns FALSE, not TRUE! This breaks every assumption about equality. Your mind will explode! Watch now!
#sql #sqltricks #database #sqltutorial #sqlweird #nullcomparison #sqlquiz #codingchallenge #sqlshorts #sqlwtf #databasequeries #sqlbugs
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COALESCE(NULL, NULL, NULL) Returns WHAT?!
COALESCE with all NULLs returns something that defies logic! This function is supposed to return first non-NULL but what if all are NULL? Watch!
#sql #sqltricks #database #sqltutorial #coalesce #nullhandling #sqlquiz #codingchallenge #sqlshorts #sqlbugs #nullfunctions #sqlwtf
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EXISTS vs IN With NULL Breaks Logic!
EXISTS and IN behave completely differently with NULL! One works, one doesn't. This breaks subquery logic! Watch the chaos!
#sql #sqltricks #database #sqltutorial #existsin #subqueries #sqlquiz #codingchallenge #sqlshorts #sqlbugs #nullhandling #sqlwtf
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NULLIF(5, 5) Returns NULL?!
NULLIF with same values returns NULL instead of the value! This function behavior will break your brain. Watch the reveal!
#sql #sqltricks #database #sqltutorial #nullif #nullhandling #sqlquiz #codingchallenge #sqlshorts #sqlbugs #nullfunctions #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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ORDER BY NULLs Go WHERE?!
ORDER BY with NULLs creates chaos! NULLs can go first or last depending on database. This breaks sorting logic! Watch!
#sql #sqltricks #database #sqltutorial #orderby #nullhandling #sqlquiz #codingchallenge #sqlshorts #sqlbugs #sorting #sqlwtf
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SUM - AVG With Zero Rows Returns WHAT?!
Aggregate functions with zero rows return NULL, not zero! SUM of nothing is NULL, not 0. This breaks aggregate logic! Watch!
#sql #sqltricks #database #sqltutorial #aggregate #zerorows #sqlquiz #codingchallenge #sqlshorts #sqlbugs #aggregatefunctions #sqlwtf
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SUM Of Empty Set Returns WHAT?!
SUM of an empty set or all NULLs returns something unexpected! This breaks all math assumptions. Your mind will explode! Watch now!
#sql #sqltricks #database #sqltutorial #sum #aggregate #sqlquiz #codingchallenge #sqlshorts #sqlbugs #nullhandling #sqlwtf
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AVG Ignores NULL Values?!
AVG function silently ignores NULL values! This creates averages that are mathematically wrong. This breaks financial calculations! Watch!
#sql #sqltricks #database #sqltutorial #avg #aggregate #sqlquiz #codingchallenge #sqlshorts #sqlbugs #nullhandling #sqlwtf
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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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MAX - MIN With All NULLs Returns WHAT?!
MAX and MIN with all NULL values return something impossible! These functions are supposed to find extremes but what about NULLs? Watch!
#sql #sqltricks #database #sqltutorial #maxmin #aggregate #sqlquiz #codingchallenge #sqlshorts #sqlbugs #nullhandling #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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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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DISTINCT With Multiple NULLs?!
DISTINCT treats all NULLs as the same value! Multiple NULLs become one. This breaks uniqueness logic. Watch the reveal!
#sql #sqltricks #database #sqltutorial #distinct #nullhandling #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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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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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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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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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
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LIKE 'test_%' Matches WHAT?!
LIKE with underscore matches ANY single character! 'test_%' matches 'test1', 'testA', 'test_'. This breaks pattern matching! Watch!
#sql #sqltricks #database #sqltutorial #like #patternmatching #sqlquiz #codingchallenge #sqlshorts #sqlbugs #wildcards #sqlwtf
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AND/OR With NULL Breaks Logic!
SQL boolean logic with NULL creates chaos! AND/OR operations with NULL give results that make NO sense. This is why queries fail! Watch now!
#sql #sqltricks #database #sqltutorial #booleanlogic #nullhandling #sqlquiz #codingchallenge #sqlshorts #sqlweird #databasequeries #sqlbugs