Question

我最近一直在学习Python，并学会了如何连接数据库并使用MYSQLdb从数据库中检索数据。但是，所有示例都显示了如何获取多行数据。我想知道如何只检索一行数据。

这是我目前的方法。

cur.execute("SELECT number, name FROM myTable WHERE id='" + id + "'")
results = cur.fetchall()
number = 0
name = ""
for result in results:
    number = result['number']
    name = result['name']

for result in results:似乎多余，因为我知道只有一个结果。

如何在不使用for循环的情况下获取一行数据？

Answer 1

.fetchone()救援：

result = cur.fetchone()

Answer 2

使用extension DFTransaction { @NSManaged private var primitiveBaseAmount: NSDecimalNumber var baseAmount: Decimal { get { willAccessValue(forKey: "baseAmount") defer { didAccessValue(forKey: "baseAmount") } return primitiveBaseAmount.decimalValue } set { willChangeValue(forKey: "baseAmount") defer { didChangeValue(forKey: "baseAmount") } primitiveBaseAmount = NSDecimalNumber(decimal: newValue) } } } [appname]`@objc DFTransaction.baseAmount.getter: 0x100343cd0 <+0>: stp x29, x30, [sp, #-16]! 0x100343cd4 <+4>: mov x29, sp 0x100343cd8 <+8>: sub sp, sp, #96 ; =96 0x100343cdc <+12>: stur x0, [x29, #-32] 0x100343ce0 <+16>: stur x8, [x29, #-40] 0x100343ce4 <+20>: bl 0x10051ca64 ; symbol stub for: objc_retain 0x100343ce8 <+24>: sub x8, x29, #24 ; =24 0x100343cec <+28>: ldur x30, [x29, #-32] 0x100343cf0 <+32>: str x0, [sp, #48] 0x100343cf4 <+36>: mov x0, x30 0x100343cf8 <+40>: bl 0x100343da4 ; [appname].DFTransaction.baseAmount.getter : __C.Decimal at DFTransaction.swift:64 0x100343cfc <+44>: ldur w9, [x29, #-24] 0x100343d00 <+48>: ldurh w10, [x29, #-20] 0x100343d04 <+52>: ldurh w11, [x29, #-18] 0x100343d08 <+56>: ldurh w12, [x29, #-16] 0x100343d0c <+60>: ldurh w13, [x29, #-14] 0x100343d10 <+64>: ldurh w14, [x29, #-12] 0x100343d14 <+68>: ldurh w15, [x29, #-10] 0x100343d18 <+72>: ldurh w16, [x29, #-8] 0x100343d1c <+76>: ldurh w17, [x29, #-6] 0x100343d20 <+80>: ldur x0, [x29, #-32] 0x100343d24 <+84>: str w9, [sp, #44] 0x100343d28 <+88>: str w10, [sp, #40] 0x100343d2c <+92>: str w11, [sp, #36] 0x100343d30 <+96>: str w12, [sp, #32] 0x100343d34 <+100>: str w13, [sp, #28] 0x100343d38 <+104>: str w14, [sp, #24] 0x100343d3c <+108>: str w15, [sp, #20] 0x100343d40 <+112>: str w16, [sp, #16] 0x100343d44 <+116>: str w17, [sp, #12] 0x100343d48 <+120>: bl 0x10051ca58 ; symbol stub for: objc_release 0x100343d4c <+124>: ldr w9, [sp, #44] 0x100343d50 <+128>: ldur x8, [x29, #-40] -> 0x100343d54 <+132>: str w9, [x8] //EXC_BAD_ACCESS 0x100343d58 <+136>: ldr w10, [sp, #40] 0x100343d5c <+140>: strh w10, [x8, #4] 0x100343d60 <+144>: ldr w11, [sp, #36] 0x100343d64 <+148>: strh w11, [x8, #6] 0x100343d68 <+152>: ldr w12, [sp, #32] 0x100343d6c <+156>: strh w12, [x8, #8] 0x100343d70 <+160>: ldr w13, [sp, #28] 0x100343d74 <+164>: strh w13, [x8, #10] 0x100343d78 <+168>: ldr w14, [sp, #24] 0x100343d7c <+172>: strh w14, [x8, #12] 0x100343d80 <+176>: ldr w15, [sp, #20] 0x100343d84 <+180>: strh w15, [x8, #14] 0x100343d88 <+184>: ldr w16, [sp, #16] 0x100343d8c <+188>: strh w16, [x8, #16] 0x100343d90 <+192>: ldr w17, [sp, #12] 0x100343d94 <+196>: strh w17, [x8, #18] 0x100343d98 <+200>: mov sp, x29 0x100343d9c <+204>: ldp x29, x30, [sp], #16 0x100343da0 <+208>: ret

.pop()

在MYSQLdb中选择单个项目 - Python

2 个答案: