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@stepbystep001

ومـما زادني شـرفـاً وتـيــهـاً
وكدت بأخمصي أطأ الـثريا
دخولي تحت قولك يا عبادي
وأن صـيَّرت أحمد لي نـبيـا
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Unexpected outcomes can result from NULL's unwillingness
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To obtain the top 15 contributors by contribution, let's utilize the … keyword
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89%
LIMIT
10%
WHERE
1%
IF
Any sequence of zero or more letters will match the … sign
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28%
_
72%
%
which denotes any single character, is next
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16%
%
11%
.
74%
_
General structure of functions is KEYWORD (ARG1, ARG2, ARG3).
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7%
F
search will return the lower-case version
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2%
SUBSTR()
2%
TRIM()
3%
UPPER()
93%
LOWER()
SUBSTR() : Trimming white space off each side of a string
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T
72%
F
Takes the string we hand it in parentheses and returns a part of the string.
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SUBSTR()
12%
TRIM()
Update all row to trim spaces in the ‘state’ field
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85%
UPDATE contributors SET state = TRIM(state)
15%
UPDATE contributors SET state = state.trim()
Concatenate operator
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5%
|
84%
||
4%
&
7%
+
How many distinct ZIP Codes, for instance, are there in the table?
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SELECT COUNT(zip) FROM contributors
81%
SELECT COUNT(DISTINCT zip) FROM contributors
What is the maximum amount that any of our contributors has given?
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SELECT MAX(amount) FROM contributors
6%
SELECT MAXIMUM(amount) FROM contributors
What if we were interested in learning who had given the largest amount? We then use …
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21%
super queries
79%
sub queries
SELECT id FROM contributors WHERE amount = (SELECT MAX(amount) FROM contributors
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16%
Using Two Queries
84%
Using sub queries
WHERE clause can use aggregate functions.
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T
51%
F