#sqlwtf — Public Fediverse posts
Live and recent posts from across the Fediverse tagged #sqlwtf, aggregated by home.social.
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One DELETE Cascades To 3.5 MILLION Rows?!
PRODUCTION APOCALYPSE! Deleted ONE user and CASCADE deleted 3.5 MILLION rows across 4 tables! Orders, payments, everything GONE! This is the scariest SQL behavior! Watch this nightmare!
#sql #sqldisaster #cascadedelete #foreignkey #productionbug #dataloss #sqlfails #massdeletion #sqlshorts #databasedisaster #sqlwtf #cascadenightmare
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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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JSON Column Search Takes 47 SECONDS Breaking Black Friday?!
JSON SEARCH NIGHTMARE! Can't index JSON columns in older MySQL! Every product search scans 2 MILLION rows! 47-second queries! Server MELTS on Black Friday! $4.7M revenue LOST! Watch the horror!
#sql #sqldisaster #json #performance #noindex #slowquery #sqlfails #blackfriday #sqlshorts #databasedisaster #sqlwtf #jsonsearch
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DELETE Without WHERE Deletes EVERYTHING?!
STOP RIGHT NOW! Forgot WHERE clause in DELETE? Your ENTIRE table is GONE! 10 million users DELETED in production! This is every developer's NIGHTMARE! Watch this disaster!
#sql #sqldisaster #delete #productionbug #sqlfails #codingnightmare #sqlshorts #databasedisaster #careerendingbug #sqlwtf #deletewithoutwhere #dataloss
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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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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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CHAR vs VARCHAR Comparison Returns ZERO Rows?!
STRING COMPARISON IS BROKEN! CHAR pads with spaces, VARCHAR doesn't! 'test' does NOT equal 'test '! Your WHERE clause returns ZERO rows! This breaks string matching! Watch!
#sql #sqlbug #char #varchar #trailingspaces #comparisonfails #sqlfails #productionbug #sqlshorts #sqlwtf #stringcomparison #padding
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TRUNCATE Can't Be Rolled Back?!
Your brain will EXPLODE! TRUNCATE looks safe but ROLLBACK won't save you! Data is PERMANENTLY DELETED even in a transaction! This broke a production database! Watch the horror!
#sql #sqldisaster #truncate #rollback #transaction #productionbug #sqlfails #dataloss #sqlshorts #databasedisaster #sqlwtf #permanentdelete
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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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CHAR vs VARCHAR Padding?!
CHAR PADS with spaces! VARCHAR doesn't. LENGTH() returns different values for same string in CHAR vs VARCHAR. This padding will break comparisons!
#sql #sqltricks #char #varchar #padding #sqlweird #sqlquiz #codingchallenge #sqlshorts #sqlwtf #stringtypes #advancedsql
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Conditional Aggregation with CASE?!
CASE inside SUM creates conditional aggregation! You can sum only certain rows based on conditions. This conditional math will transform your data!
#sql #sqltricks #case #sum #conditionalaggregation #sqlweird #sqlquiz #codingchallenge #sqlshorts #sqlwtf #aggregation #advancedsql
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UTF8MB4 Emoji Support EXPLODES Table From 500GB to 2TB?!
CHARACTER SET BOMB! Changed to utf8mb4 for emoji support! Table size EXPLODES 4x overnight! 500GB becomes 2.1TB! Disk fills up during ALTER! Database goes READ-ONLY! Watch this explosion!
#sql #sqldisaster #utf8mb4 #emoji #storageexplosion #altertable #sqlfails #diskfull #sqlshorts #databasedisaster #sqlwtf #characterset
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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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Index On NULL Column Does NOTHING?!
Your performance just DIED! Created an index but queries with NULL are still slow? Indexes IGNORE NULL values! Full table scan on millions of rows! Your index is USELESS! Watch the disaster!
#sql #sqlperformance #index #null #fulltablescan #slowquery #sqlfails #productionbug #sqlshorts #databasedisaster #sqlwtf #indextrap
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UPDATE With JOIN Corrupts Your Data?!
DATA CORRUPTION ALERT! UPDATE with JOIN can update the SAME row MULTIPLE times! $100 product gets THREE discounts applied = $51! Your prices are WRONG! Watch this disaster!
#sql #sqldisaster #update #join #datacorruption #productionbug #sqlfails #multipleupdates #sqlshorts #databasedisaster #sqlwtf #updatechaos
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Date Arithmetic with Leap Year?!
Leap years BREAK date math! February 28 + 1 day = February 29 in leap years, March 1 in non-leap years. This edge case will cause bugs!
#sql #sqltricks #datearithmetic #leapyear #dateadd #sqlweird #sqlquiz #codingchallenge #sqlshorts #sqlwtf #datefunctions #advancedsql
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LAG - LEAD Default Value Trap?!
LAG and LEAD have DEFAULT values! When there's no previous/next row, they return the default. This hidden parameter will surprise you!
#sql #sqltricks #lag #lead #defaultvalue #sqlweird #sqlquiz #codingchallenge #sqlshorts #sqlwtf #windowfunctions #advancedsql
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NULLIF and COALESCE Chain?!
NULLIF and COALESCE can be CHAINED! NULLIF converts to NULL, COALESCE converts from NULL. This transformation chain will surprise you!
#sql #sqltricks #nullif #coalesce #functionchaining #sqlweird #sqlquiz #codingchallenge #sqlshorts #sqlwtf #nullhandling #advancedsql
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Window PARTITION BY Changes Results?!
PARTITION BY creates separate windows! Each partition has its own running sum. This partitioning will change your aggregation results!
#sql #sqltricks #partitionby #windowfunctions #runningsum #sqlweird #sqlquiz #codingchallenge #sqlshorts #sqlwtf #advancedsql
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Auto-Increment IDs Have GAPS Forever?!
IDs are BROKEN! Failed INSERT consumes the auto-increment ID! User #1, skip #2, User #3! Your IDs have permanent GAPS! This breaks ID-based logic! Watch this chaos!
#sql #sqlbug #autoincrement #primarykey #idgaps #failedinsert #sqlfails #productionbug #sqlshorts #sqlwtf #identitycolumn #dataintegrity
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DateTime Timezone Shift Costs $2.3M In Missed Flights?!
TIMEZONE APOCALYPSE! Flight times stored WITHOUT timezone! UTC 14:00 displays as 2 PM but IS 11 AM local! 470 passengers MISSED flights in ONE day! Airlines lost $2.3M! Watch this disaster!
#sql #sqldisaster #timezone #datetime #productionbug #dataloss #sqlfails #airlinedisaster #sqlshorts #databasedisaster #sqlwtf #timestamphell
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DateTime Timezone Shift Costs $2.3M In Missed Flights?!
TIMEZONE APOCALYPSE! Flight times stored WITHOUT timezone! UTC 14:00 displays as 2 PM but IS 11 AM local! 470 passengers MISSED flights in ONE day! Airlines lost $2.3M! Watch this disaster!
#sql #sqldisaster #timezone #datetime #productionbug #dataloss #sqlfails #airlinedisaster #sqlshorts #databasedisaster #sqlwtf #timestamphell
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DateTime Timezone Shift Costs $2.3M In Missed Flights?!
TIMEZONE APOCALYPSE! Flight times stored WITHOUT timezone! UTC 14:00 displays as 2 PM but IS 11 AM local! 470 passengers MISSED flights in ONE day! Airlines lost $2.3M! Watch this disaster!
#sql #sqldisaster #timezone #datetime #productionbug #dataloss #sqlfails #airlinedisaster #sqlshorts #databasedisaster #sqlwtf #timestamphell
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DateTime Timezone Shift Costs $2.3M In Missed Flights?!
TIMEZONE APOCALYPSE! Flight times stored WITHOUT timezone! UTC 14:00 displays as 2 PM but IS 11 AM local! 470 passengers MISSED flights in ONE day! Airlines lost $2.3M! Watch this disaster!
#sql #sqldisaster #timezone #datetime #productionbug #dataloss #sqlfails #airlinedisaster #sqlshorts #databasedisaster #sqlwtf #timestamphell
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DATE_FORMAT with Edge Cases?!
DATE_FORMAT has HUNDREDS of format codes! %j is day of year, %W is weekday name. This formatting language will confuse you!
#sql #sqltricks #dateformat #formatcodes #dateformatting #sqlweird #sqlquiz #codingchallenge #sqlshorts #sqlwtf #datefunctions #advancedsql
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JSON Path Expressions Extract Data?!
JSON_EXTRACT uses PATH syntax! The $ symbol means root, . means property access. This JSON path language will confuse you!
#sql #sqltricks #jsonextract #jsonpath #jsonunquote #sqlweird #sqlquiz #codingchallenge #sqlshorts #sqlwtf #jsonfunctions #advancedsql
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String Collation Changes Comparison?!
Collation CHANGES string comparison! Case-insensitive collation makes 'A' = 'a'. This hidden setting will break your WHERE clauses!
#sql #sqltricks #collation #stringcomparison #casesensitivity #sqlweird #sqlquiz #codingchallenge #sqlshorts #sqlwtf #stringfunctions #advancedsql
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Self-Join with Aliases Trap?!
Self-joins need DIFFERENT aliases! Same table, different names. The join condition creates relationships within the same table. This will confuse you!
#sql #sqltricks #selfjoin #aliases #tablealiases #sqlweird #sqlquiz #codingchallenge #sqlshorts #sqlwtf #joins #advancedsql
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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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NTH_VALUE Gets Specific Position?!
NTH_VALUE extracts the Nth value from window! It's like array indexing for window functions. This positional access will surprise you!
#sql #sqltricks #nthvalue #windowfunctions #positionalaccess #sqlweird #sqlquiz #codingchallenge #sqlshorts #sqlwtf #advancedsql
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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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Correlated Subquery in SELECT?!
Subqueries in SELECT execute for EVERY row! This correlated subquery runs once per row, creating a performance nightmare. This is why queries are slow!
#sql #sqltricks #correlatedsubquery #selectclause #performance #sqlweird #sqlquiz #codingchallenge #sqlshorts #sqlwtf #subqueries #advancedsql