In HarmonyOS, the addition, deletion and modification of relational database is a very common technology. Today, I will write a demo to explain the addition, deletion and modification of data in detail. Before development, we need to learn " relational database " and " result set ". This development document is described in three steps: "Api use", "demo implementation", and "operation effect"
1. API usage
1.1 Create a database
import dataRdb from '@ohos.data.rdb'
const STORE_CONFIG = {name: "RdbTest.db" }
const SQL_CREATE_TABLE = "CREATE TABLE IF NOT EXISTS EMPLOYEE (ID INTEGER PRIMARY KEY AUTOINCREMENT, NAME TEXT NOT NULL, AGE INTEGER, SALARY REAL, CODES BLOB)"
let promise = dataRdb.getRdbStore(STORE_CONFIG, 1);
promise.then(async (rdbStore) => {
rdbStore.executeSql(SQL_CREATE_TABLE, null)
}).catch((err) => {
expect(null).assertFail();
})
1.2 Insert data
const valueBucket = {
"NAME": "Lisa",
"AGE": 18,
"SALARY": 100.5,
"CODES": new Uint8Array([1, 2, 3, 4, 5]),
}
rdbStore.insert("EMPLOYEE", valueBucket, function (err, ret) {
expect(1).assertEqual(ret)
console.log(TAG + "insert first done: " + ret)})
1.3 Deleting data
let predicates = new dataRdb.RdbPredicates("EMPLOYEE")
predicates.equalTo("NAME", "Lisa")
rdbStore.delete(predicates, function (err, rows) {
console.log(TAG + "delete rows: " + rows)})
1.4 Modify data
const valueBucket = {
"NAME": "Rose",
"AGE": 22,
"SALARY": 200.5,
"CODES": new Uint8Array([1, 2, 3, 4, 5]),
}
let predicates = new dataRdb.RdbPredicates("EMPLOYEE")
predicates.equalTo("NAME", "Lisa")
rdbStore.update(valueBucket, predicates, function (err, ret) {
console.log(TAG + "updated row count: " + ret)})
1.5 Query data
let predicates = new dataRdb.RdbPredicates("EMPLOYEE")
predicates.equalTo("NAME", "Rose")
rdbStore.query(predicates, ["ID", "NAME", "AGE", "SALARY", "CODES"], function (err, resultSet) {
console.log(TAG + "resultSet column names:" + resultSet.columnNames)
console.log(TAG + "resultSet column count:" + resultSet.columnCount)})
1.6 Result set processing
resultSet.goToFirstRow()
const id = resultSet.getLong(resultSet.getColumnIndex("ID"))
const name = resultSet.getString(resultSet.getColumnIndex("NAME"))
const age = resultSet.getLong(resultSet.getColumnIndex("AGE"))
const salary = resultSet.getDouble(resultSet.getColumnIndex("SALARY"))
2. Demo implementation
We write five texts, namely "create database", "insert data", "query data", "modify data", "delete data", and implement corresponding click events in turn. All the codes are as follows
import dataRdb from '@ohos.data.rdb'
@Entry
@Component
struct MyRdb {
rdb: dataRdb.RdbStore;
@State name: string= "Lisa"
private CreateRdbStore() {
var that=this;
dataRdb.getRdbStore({ name: "XiLeiRgb.db" }, 1, function (err, rdbStore) {
if (err) {
console.log('获取失败' + err)
} else {
const SQL_CREATE_TABLE = "CREATE TABLE IF NOT EXISTS EMPLOYEE (ID INTEGER PRIMARY KEY AUTOINCREMENT, NAME TEXT NOT NULL, AGE INTEGER, SALARY REAL, CODES BLOB)"
rdbStore.executeSql(SQL_CREATE_TABLE, null)
console.log('创建成功')
that.rdb=rdbStore;
}
})
}
private insertData() {
const valueBucket = {
"NAME": "Lisa",
"AGE": 18,
"SALARY": 100.5,
"CODES": new Uint8Array([1, 2, 3, 4, 5]),
}
let promise = this.rdb.insert("EMPLOYEE", valueBucket)
promise.then(async (ret) => {
console.log( "插入成功==>>insert first done: " + ret)
this.name="Lisa";
}).catch((err) => {
})
}
private SelectData() {
let predicates = new dataRdb.RdbPredicates("EMPLOYEE")
predicates.equalTo("NAME", this.name)
console.log("查询条件====>"+this.name)
this.rdb.query(predicates, ["ID", "NAME", "AGE", "SALARY", "CODES"], function (err, resultSet) {
console.log("查询成功==>>resultSet column names:" + resultSet.columnNames)
console.log("查询成功==>>resultSet column count:" + resultSet.columnCount)
if(resultSet.rowCount>0){
resultSet.goToFirstRow()
const id = resultSet.getLong(resultSet.getColumnIndex("ID"))
const name = resultSet.getString(resultSet.getColumnIndex("NAME"))
const age = resultSet.getLong(resultSet.getColumnIndex("AGE"))
const salary = resultSet.getDouble(resultSet.getColumnIndex("SALARY"))
console.log( "id===>" + id+"===name==>"+name+"==age==>"+age+"==salary==>"+JSON.toString(salary))
}else{
console.log("暂无数据")
}
})
}
private updateData() {
var that=this;
let valueBucket = {
"NAME": "Rose",
"AGE": 22,
"SALARY": 200.5,
"CODES": new Uint8Array([1, 2, 3, 4, 5]),
}
let predicates = new dataRdb.RdbPredicates("EMPLOYEE")
predicates.equalTo("NAME", this.name)
that.rdb.update(valueBucket, predicates, function (err, ret) {
console.log("修改成功==>>updated row count: " + ret)
that.name = "Rose";
})
}
private deleteData() {
let that=this
let predicates = new dataRdb.RdbPredicates("EMPLOYEE")
predicates.equalTo("NAME", this.name)
that.rdb.delete(predicates, function (err, rows) {
console.log("删除成功===>>delete rows: " + rows)
})
}
build() {
Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) {
Text('创建数据库')
.fontSize(50)
.onClick(this.CreateRdbStore.bind(this))
.fontWeight(FontWeight.Bold)
Text('插入数据')
.fontSize(50)
.onClick(this.insertData.bind(this))
.backgroundColor(Color.Red)
.fontWeight(FontWeight.Bold)
Text('查询数据')
.fontSize(50)
.onClick(this.SelectData.bind(this))
.backgroundColor(Color.White)
.fontWeight(FontWeight.Bold)
Text('修改数据')
.fontSize(50)
.onClick(this.updateData.bind(this))
.backgroundColor(Color.Red)
.fontWeight(FontWeight.Bold)
Text('删除数据')
.fontSize(50)
.onClick(this.deleteData.bind(this))
.backgroundColor(Color.White)
.fontWeight(FontWeight.Bold)
}
.width('100%')
.height('100%')
}
}
The interface effect is as follows
3. Operation effect
We click "Create Database", "Insert Data", "Query Data", "Modify Data", "Query Data", "Delete Data", "Query Data" and the effect is as follows
{{o.name}}
{{m.name}}