英文:
Use one struct for multiple SQL queries
问题
我有多个类似的SQL查询需要在Go代码中运行。像这样的：
type S1 struct {
X int
Y int
Z string
}
rows, err := db.Queryx("SELECT X,Y,Z FROM SomeTable")
for rows.Next() {
var p S1
err = rows.StructScan(&p)
}
type S2 struct {
Y int
Z string
}
rows, err := db.Queryx("SELECT Y,Z FROM SomeTable")
for rows.Next() {
var p S2
err = rows.StructScan(&p)
}
type S3 struct {
X int
Y int
}
rows, err := db.Queryx("SELECT X,Y FROM SomeTable")
for rows.Next() {
var p S3
err = rows.StructScan(&p)
}
有没有办法在这3个查询中使用一个结构体？理想情况下，希望能使用S1结构体来处理这3个查询。可能很重要的一点是，使用的是Clickhouse数据库。SqlX文档并没有说明这是否可能，所以我想自己尝试弄清楚...
英文:
I have multiple similar SQL queries that I need to run in Go code.<br/>
Something like this:<br/>
type S1 struct {
X int
Y int
Z string
}
rows, err := db.Queryx("SELECT X,Y,Z FROM SomeTable")
for rows.Next() {
var p S1
err = rows.StructScan(&p)
}
type S2 struct {
Y int
Z string
}
rows, err := db.Queryx("SELECT Y,Z FROM SomeTable")
for rows.Next() {
var p S2
err = rows.StructScan(&p)
}
type S3 struct {
X int
Y int
}
rows, err := db.Queryx("SELECT X,Y FROM SomeTable")
for rows.Next() {
var p S3
err = rows.StructScan(&p)
}
Is there a way to use one struct for all 3 queries? <br/>
Ideally S1 being used for all 3 queries would be great.<br/>
Maybe it is important, Clickhouse database is being used.<br/>
SqlX documentation does not imply this is possible, hence the question while I try to figure it out on my own...
答案1
得分: 1
从这里获取答案：https://go.dev/doc/database/querying#multiple_rows
使用Scan方法，您可以为查询结果的每个查询列分配一个变量。
注意：未由scan()填充的值将默认为字段类型的零值。
type S1 struct {
X int
Y int
Z string
}
func run() {
rows, err := db.Queryx("SELECT X,Y,Z FROM SomeTable")
for rows.Next() {
var p S1
err = rows.Scan(&p.X, &p.Y, &p.Z)
}
rows, err := db.Queryx("SELECT Y,Z FROM SomeTable")
for rows.Next() {
var p S1
err = rows.Scan(&p.Y, &p.Z)
}
rows, err := db.Queryx("SELECT X,Y FROM SomeTable")
for rows.Next() {
var p S1
err = rows.Scan(&p.X, &p.Y)
}
}
英文:
Answer taken from here: https://go.dev/doc/database/querying#multiple_rows
Using the Scan method you can assign populate one variable for every query Column of the query result.
Note: the values not populated by scan(), will default to the zero value of the field type.
type S1 struct {
X int
Y int
Z string
}
func run() {
rows, err := db.Queryx("SELECT X,Y,Z FROM SomeTable")
for rows.Next() {
var p S1
err = rows.Scan(&S1.X, &S1.Y, &S1.Z)
}
rows, err := db.Queryx("SELECT Y,Z FROM SomeTable")
for rows.Next() {
var p S1
err = rows.Scan(&S1.Y, &S1.Z)
}
rows, err := db.Queryx("SELECT X,Y FROM SomeTable")
for rows.Next() {
var p S1
err = rows.Scan(&S1.X, &S1.Y)
}
}
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