The react-native component I created through React.createClass doesn’t seem to bind the this keyword correctly, preventing me from accessing this.state. This is the error I get:
The cod
Tag: Constraint
Mysql: Error 1215 (HY000): Unable to add foreign key constraints
I have read about database system concepts, 6th edition, Silberschatz. I will implement the university database system shown in Chapter 2 on MySQL’s OS X. But I’m in the course of creating tables I
Constrained generic type to inherit the generic type in F #
let mapTuple f (a,b) = (fa, fb) I am trying to create a function to apply function f to a tuple And return the result as a tuple. F# type inference says that mapTuple returns a’b *’b tuple. It also
Haskell – Unclear Type Variables of Dependent Constraints
I am writing a new authentication system for the Snap web framework, because the built-in authentication system is not modular enough, and it has some redundancy/”self-respect” features. However, t
[PowerDesigner] ConsTRAINT Name Uniqueness Problem and Processing
Using PowerDesigner to generate a database script, a Constraint name uniqueness error is reported:
Double click each Line error, found that the foreign key quoted names are duplicated:
Day41 – numeric type, integrity constraint
day41 Numeric type Integer type
mysql> create table t1(id tinyint); # The default is signed, that is, there is a sign before the number Unsigned setting mysql> create table t1(id tinyint uns
PostgreSQL – Postgres unique constraint is not forced uniqueness
This is my constraint:
CREATE UNIQUE INDEX index_subscriptions_on_user_id_and_class_type_id_and_deleted_at
ON subscriptions
USING btree
(user_id, class_type_id, deleted_at); This query pr
Database – SQLite – Table Constraints Unique and Column Constraints Unique Differences between UniQue?
Questions about SQLite.
In CREATE TABLE SQL, we can add UNIQUE constraints in any way: column-constraint or table-constraint. My question is simple. Do they work differently?
The only d