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?
答案 0 :(得分:6)
.fetchone()
救援:
result = cur.fetchone()
答案 1 :(得分:1)
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()