如何在SQLite中添加外键？

Question

我尝试添加外键，但iam收到错误消息“ ALTER TABLE事务添加了CONSTRAINT -结果：在“ CONSTRAINT”附近：语法错误” 这是我的剧本，我的剧本怎么了？

CREATE TABLE if not EXISTS User(
RekeningID INTEGER PRIMARY KEY AUTOINCREMENT,
NamaBank varchar(10) NOT NULL,
AtasNama varchar(15) NOT NULL,
NomerRekening INT(15) NOT NULL);

CREATE TABLE IF NOT EXISTS Transactions(
UangMasukID Integer PRIMARY KEY AUTOINCREMENT,
TerimaDari varChar(20) NOT NULL,
Keterangan varChar(100) NOT NULL,
Jumlah int(9) NOT NULL
);

ALTER TABLE Transactions ADD CONSTRAINT FK_REK(rekID) FOREIGN KEY (rekID) 
REFERENCES User(RekeningID);