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App Inventor 2 SQLite 拓展：超流行兼容主流SQL语法的迷你本地数据库引擎...
...数据表
创建一个测试数据表，sql如下：
CREATE TABLE users (
id INTEGER PRIMARY KEY,
name TEXT,
age INTEGER);
数据表信息
这时，可以查看一下表信息：
插入数据
往 users 表中插入...
Database design for a survey [closed]
... would be the best way to implement this in the database, specifically the tables required. The survey contains different types of questions. For example: text fields for comments, multiple choice questions, and possibly questions that could contain more than one answer (i.e. check all that apply).
...
How to get ERD diagram for an existing database?
...ings (also called referential integrity constraints) in a graph style. The table nodes and relations are layed out automatically, with a number of layout modes available. The resulting graph is unique as it displays all information in an optimal and readable layout.
from its site
...
SQL server query to get the list of columns in a table along with Data types, NOT NULL, and PRIMARY
... to write a query on SQL server to get the list of columns in a particular table, its associated data types (with length) and if they are not null. And I have managed to do this much.
...
Postgres: INSERT if does not exist already
...
There is one caveat/side effect. In a table with sequence column (serial or bigserial), even if no row is inserted the sequence is incremented at every insert attempt.
– Grzegorz Luczywo
Jul 2 '17 at 12:10
...
T-SQL: Opposite to string concatenation - how to split string into multiple records [duplicate]
...le gem:
CREATE FUNCTION dbo.Split (@sep char(1), @s varchar(512))
RETURNS table
AS
RETURN (
WITH Pieces(pn, start, stop) AS (
SELECT 1, 1, CHARINDEX(@sep, @s)
UNION ALL
SELECT pn + 1, stop + 1, CHARINDEX(@sep, @s, stop + 1)
FROM Pieces
WHERE stop > 0
)
S...
Retrieve column names from java.sql.ResultSet
...tSetMetaData
e.g.
ResultSet rs = stmt.executeQuery("SELECT a, b, c FROM TABLE2");
ResultSetMetaData rsmd = rs.getMetaData();
String name = rsmd.getColumnName(1);
and you can get the column name from there. If you do
select x as y from table
then rsmd.getColumnLabel() will get you the retri...
“INSERT IGNORE” vs “INSERT … ON DUPLICATE KEY UPDATE”
...into a column with a NOT NULL constraint.
Inserting a row to a partitioned table, but the values you insert don't map to a partition.
If you use REPLACE, MySQL actually does a DELETE followed by an INSERT internally, which has some unexpected side effects:
A new auto-increment ID is allocated....
How to implement a many-to-many relationship in PostgreSQL?
I believe the title is self-explanatory. How do you create the table structure in PostgreSQL to make a many-to-many relationship.
...
method of iterating over sqlalchemy model's defined columns?
... it is actually much easier because if you inherit from Base, you have a __table__ attribute, so that you can do:
for c in JobStatus.__table__.columns:
print c
for c in JobStatus.__table__.foreign_keys:
print c
See How to discover table properties from SQLAlchemy mapped object - similar ...