Are you a second-year Computer Science student at the University of Cape Town looking for a comprehensive study aid to excel in your practicals, tests, and exams? Look no further! These meticulously crafted digital lecture notes cover databases.
Insert:
INSERT INTO <TableName>
VALUES (<Col1Value>, <Col2Value>, ... , <ColnValue>);
Insert (Nested): Data Types:
INSERT INTO <TableName> INTEGER, FLOAT,
VALUES (<SelectQuery>); ENUM(v,v,v,v,v), DOUBLE, REAL,
NUMERIC, BIT, VARCHAR, DATE
Table Creation: etc. (see slides)
CREATE TABLE <NewTableName> Null Handling:
NULL -> Allows Null Values
(<Col1Name> <DataType> <NullHandling>,
NOT NULL -> No Null Values
<Col2Name> <DataType> <NullHandling>,
...
<ColnName> <DataType> <NullHandling>,
PRIMARY KEY (<ColiName>, ... ,<ColjName>),
CHECK (<ColiName> IN (<SelectQueryOnPKeyOrigin>))
CHECK (<ColjName> IN (<SelectQueryOnPKeyOrigin>))
);
Retrieve:
Select Specific Columns of Row:
SELECT <Col1Name>, ... ,<ColnName>
FROM <TableName>;
Select All Columns of Row:
SELECT *
FROM <TableName>;
Select Ordered (Ascending):
SELECT <ColiName>
FROM <TableName>
ORDER BY <Col1Name>, ... ,<ColnName>;
Select Ordered (Descending):
SELECT <ColiName>
FROM <TableName>
ORDER BY <Col1Name>, ... ,<ColnName> DESC;
Select By Logical Condition:
SELECT <ColiName>
2
, BEN FROST
FROM <TableName>
WHERE <LogicalCondition>;
Logical Condition Configurations:
Standard Comparison:
WHERE <ColiName> = | <= | >= | < | > <Value>;
Starts With:
WHERE <ColiName> LIKE “<Value>%”;
Ends With: _ -> One Char Wildcard
WHERE <ColiName> LIKE “%<Value>”;
Contains:
WHERE <ColiName> LIKE “%<Value>%”;
&&:
WHERE <Logical1Condition> AND <Logical2Condition>;
||:
WHERE <Logical1Condition> OR <Logical2Condition>;
!:
WHERE NOT <LogicalCondition>;
Between:
WHERE <ColiName> BETWEEN <LowerBound> AND <UpperBound>;
Null/Not Null:
WHERE <ColiName> IS NULL; | WHERE <ColiName> IS NOT NULL;
Select Distinct Row:
SELECT DISTINCT <Col1Name>, ... ,<ColnName>
FROM <TableName>;
Select Top n Ordered Rows:
SELECT TOP <Value> <Col1Name>, ... ,<ColnName>
FROM <TableName>
ORDER BY <Col1Name>, ... ,<ColnName>;
, BEN FROST
-
Set Theory:
Union:
<SelectedSet> UNION <SelectedSet> Set functions all retain
Intersect: duplicates. Selected
<SelectedSet> INTERSECT <SelectedSet> relations’ structures must
match.
Except:
<SelectedSet> EXCEPT <SelectedSet>
Number Functions:
Substring From Left:
LEFT(<String>,<NumberOfChars>)
Substring From Right:
RIGHT(<String>,<NumberOfChars>)
Substring From Middle (to Right):
MID(<String>, <StartPosition> ,<NumberOfChars>)
COALESCE Function: COALESCE takes the first non-NULL
COALESCE(<Col1Name>, ... ,<ColnName>) value of the specified columns. (in order)
Deriving Functions As New Output Columns:
SELECT <FunctionOnTable> AS <NewColumnName>
FROM <TableName>;
4
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