Oracle 怎样提取除了最后三位以外数据

Question

怎样提取除了最后三位以外数据
A21.SMZXI/ZG01/01
A21.SMZXI/ZG00/02/01
A21.DAHEJ/JA3700/PX02/01

Answer 1

用substr函数，参数说明是：substr( string, start_position, [ length ] )

如：
substr('This is a test', 6, 2) would return 'is'
substr('This is a test', 6) would return 'is a test'
substr('TechOnTheNet', 1, 4) would return 'Tech'

Answer 2

substr(数据对象,1,length(数据对象) - 3)

例如：
substr('A21.SMZXI/ZG01/01',1,length('A21.SMZXI/ZG01/01') - 3)