转换

某些数据类型可以隐式或显式地转换为其他类型。

• Implictly cast to: 值可以自动转换为目标类型。
• Assigned to: 值在插入到目标类型的列时可以自动转换。
• Explictly cast to: 只有在使用 cast 函数或 :: 操作符时，值才能转换为目标类型。

From type	Implictly cast to	Assigned to	Explictly cast to
boolean		varchar	integer
smallint	integer bigint numeric real double rw_int256	varchar
integer	bigint numeric real double rw_int256	smallint	boolean
bigint	numeric real double rw_int256	smallint integer varchar
numeric	real double	smallint integer bigint varchar
real	double	smallint integer bigint numeric varchar
double		smallint integer bigint numeric real varchar
varchar			boolean smallint integer bigint numeric real double date timestamp timestamp with time zone time interval bytea jsonb rw_int256
date	timestamp timestamp with time zone	varchar
timestamp	timestamp with time zone	varchar date time
timestamp with time zone		varchar date timestamp time
time	interval	varchar
interval		varchar time
bytea		varchar
jsonb	boolean smallint integer bigint numeric real double	varchar
rw_int256		varchar

:::注意

如果嵌套的表达式和类型是可以转换的，那么 struct 之间就可以进行显式或隐式转换。

:::