KwickClips Databases and SQL

Databases and SQL: 71 short revision clips

One idea per clip, with the answer written out underneath. Each clip links back to the full Databases and SQL lesson it came from.

Are marks data or information?39 secWhat is inconsistency?40 secWhat does DBMS stand for?45 secWhere does your school store marks?39 secWhat is another word for a row?43 secWhat is the domain of marks out of 100?40 secA table has 3 columns and 4 rows. What is the cardinality?44 secWhich model allows many parents?42 secWhy can a name not be a key?39 secWhat is a candidate key?38 secWhat is an alternate key?37 secWhat is a foreign key?41 secWhat is a query?41 secIs SELECT DDL or DQL?43 secWhy does MySQL show ->?40 secWhich type stores 85.5?42 secWhy the error 'No database selected'?39 secHow do you stop two students sharing a roll number?43 secDo you have to recreate a table to add a column?40 secCan a DROP be undone?37 secWhat does a skipped column get?37 secWhy did all marks become 80?38 secHow do you delete one student?36 secHow do you confirm an UPDATE?35 secHow do you see all columns?41 secWhich operator means not equal?39 secWhich keeps more rows, AND or OR?41 secWhere is DISTINCT written?39 secIs 65 included in BETWEEN 65 AND 88?39 secWhat is IN a short form of?36 secWhat does '____' match?41 secWhy does marks = NULL return no rows?42 secWhat is the default order?39 secWhy sort by two columns?42 secWhy the error when ORDER BY comes first?39 secWhat is MOD(17, 5)?40 secDoes MID count from 0?43 secWhat is the difference between MONTH and MONTHNAME?42 secCan MONTH(dob) be used in WHERE?38 secWhat does an aggregate function return?39 secWhich COUNT counts rows?38 secCan one SELECT use four aggregates?42 secDoes AVG treat NULL as zero?42 secWhat does GROUP BY do first?36 secHow many rows does GROUP BY return?36 secWhere do aggregates belong?36 secHow many rows remain after HAVING COUNT(*) > 1?36 secWhy avoid one big table?42 sec