大约有 40,000 项符合查询结果（耗时：0.0264秒） [XML]
Joining two lists together
...eserves the order of the lists, but it doesn't remove any duplicates which Union would do.
This does change list a. If you wanted to preserve the original lists then you should use Concat (as pointed out in the other answers):
var newList = a.Concat(b);
This returns an IEnumerable as long as a i...
Union of dict objects in Python [duplicate]
How do you calculate the union of two dict objects in Python, where a (key, value) pair is present in the result iff key is in either dict (unless there are duplicates)?
...
How to import an excel file in to a MySQL database
...r Excel table into the sales table of a MySQL database named mydatabase.
Select the relevant cells:
Paste into Mr. Data Converter and select the output as MySQL:
Change the table name and column definitions to fit your requirements in the generated output:
CREATE TABLE sales (
id INT NOT N...
What is the error “Every derived table must have its own alias” in MySQL?
...er), which can the be used to refer to it in the rest of the outer query.
SELECT ID FROM (
SELECT ID, msisdn FROM (
SELECT * FROM TT2
) AS T
) AS T
In your case, of course, the entire query could be replaced with:
SELECT ID FROM TT2
...
What's the difference between utf8_general_ci and utf8_unicode_ci?
...or "ǽ" == "æ". For sorting this makes sense but could be surprising when selecting via equalities or dealing with unique indices - bugs.mysql.com/bug.php?id=16526
– Mat Schaffer
Mar 13 '15 at 15:22
...
Rails 3: Get Random Record
...You can use the following trick on an indexed column (PostgreSQL syntax):
select *
from my_table
where id >= trunc(
random() * (select max(id) from my_table) + 1
)
order by id
limit 1;
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...
Get all table names of a particular database by SQL query?
...different sql dbms deal with schemas.
Try the following
For SQL Server:
SELECT TABLE_NAME
FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_TYPE = 'BASE TABLE' AND TABLE_CATALOG='dbName'
For MySQL:
SELECT TABLE_NAME
FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_TYPE = 'BASE TABLE' AND TABLE_SCHEMA='dbN...
How to get the mysql table columns data type?
...
You can use the information_schema columns table:
SELECT DATA_TYPE FROM INFORMATION_SCHEMA.COLUMNS
WHERE table_name = 'tbl_name' AND COLUMN_NAME = 'col_name';
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im...
What does “export” do in shell programming? [duplicate]
... are copied - but for any kind of subprocess, not only for subshells. So a mysql process get value from MYSQL_PWD env var, but would have no concept of MYSQL_PWD shell var.
– David Tonhofer
Dec 24 '18 at 15:43
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LAST_INSERT_ID() MySQL
...RT INTO table2 (parentid,otherid,userid) VALUES (LAST_INSERT_ID(), 4, 1);
SELECT MAX(id) FROM table1;
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