表达式

SequoiaDB 巨杉数据库内置 SQL 支持算术表达式和比较表达式。

算术表达式

格式

<field1_name> <mathematical_operator> <value>

Note:

支持复合运算，如 select ( a + 1 ) * ( a - 1 ), b + 1 from sample.employee

示例

age 字段值+1

age + 1

取集合中age字段，age 值+1

> db.exec( "select age + 1 from sample.employee" )
{
  "age": 12
}

比较表达式

格式

<field1_name> <comparison_operator> <value | field2_name>

<field1_name> <comparison_operator> <value> <logical_operator> <field1_name> <comparison_operator> <value>

示例

• age 字段大于 11

  age > 11

  查询匹配 age 大于 11 的记录

  > db.exec( "select * from sample.employee where age > 11" )
  {
    "_id": {
    "$oid": "5aa3330fdc5673331f000000"
    },
    "name": "Lucy",
    "age": 12
  }

• age 字段大于等于 11，且 name 为“Harry”

  age >= 11 AND name = 'Harry'

  查询匹配 age 大于等于 11，且 name 为“Harry”的记录

  > db.exec( "select * from sample.employee where age >= 11 AND name = 'Harry'" )
  {
    "_id": {
    "$oid": "5aa35dbedc5673331f000001"
    },
    "name": "Harry",
    "age": 11
  }