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How do you use the “WITH” clause in MySQL?
...to write queries like this:
WITH RECURSIVE my_cte AS
(
SELECT 1 AS n
UNION ALL
SELECT 1+n FROM my_cte WHERE n<10
)
SELECT * FROM my_cte;
+------+
| n |
+------+
| 1 |
| 2 |
| 3 |
| 4 |
| 5 |
| 6 |
| 7 |
| 8 |
| 9 |
| 10 |
+------+
10 rows in set (0,00 sec)
...
Check if a class has a member function of a given signature
...her down
Check for member x in a given class. Could be var, func, class, union, or enum:
CREATE_MEMBER_CHECK(x);
bool has_x = has_member_x<class_to_check_for_x>::value;
Check for member function void x():
//Func signature MUST have T as template variable here... simpler this way :\
CREAT...
What's the difference between array_merge and array + array?
...
The difference is:
The + operator takes the union of the two arrays, whereas the array_merge function takes the union BUT the duplicate keys are overwritten.
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i...
How to select multiple rows filled with constants?
...
SELECT 1, 2, 3
UNION ALL SELECT 4, 5, 6
UNION ALL SELECT 7, 8, 9
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How to join two sets in one line without using “|”
...are assigned sets. Without using the join operator | , how can I find the union of the two sets? This, for example, finds the intersection:
...
Number of rows affected by an UPDATE in PL/SQL
...rowcount);
insert into client
select 1, 'void' from dual
union all select 4, 'void' from dual
union all select 1, 'void' from dual
union all select 6, 'void' from dual
union all select 10, 'void' from dual;
dbms_output.put_line('Number of lines affected by previous DML op...
How to get first and last day of previous month (with timestamp) in SQL Server
...st month' AS Title, CONVERT(VARCHAR, @FirstDayOfLastMonth , 120) AS [ODBC]
UNION
SELECT
'Last day of last month' AS Title, CONVERT(VARCHAR, @LastDayOfLastMonth , 120) AS [ODBC]
Run the above code to produce the following output:
Note: Bear in mind that today's date for me is 12th Septemb...
汇编语言超浓缩教程（汇编入门必备） - C/C++ - 清泛网 - 专注C/C++及内核技术
...，不同的CPU其汇编语言的指令语法亦不相同。个人电脑由1981年推出至今，其CPU发展过程为：8086→80286→80386→80486→PENTIUM →……，还有AMD、CYRIX等旁支。后面兼容前面CPU的功能，只不过多了些指令（如多能奔腾的MMX指...
Reshaping data.frame from wide to long format
...f("Select Code, Country, '1950' As Year, `1950` As Value From wide
Union All
Select Code, Country, '1951' As Year, `1951` As Value From wide
Union All
Select Code, Country, '1952' As Year, `1952` As Value From wide
Union All
Select Code, Country, '1953' A...
Include headers when using SELECT INTO OUTFILE?
...aders yourself. Something like:
SELECT 'ColName1', 'ColName2', 'ColName3'
UNION ALL
SELECT ColName1, ColName2, ColName3
FROM YourTable
INTO OUTFILE '/path/outfile'
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