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标准误差

使用示例​

import com.youngdatafan.sqlbuilder.enums.DatabaseType;
import com.youngdatafan.sqlbuilder.enums.FunctionType;
import com.youngdatafan.sqlbuilder.model.CustomSql;
import com.youngdatafan.sqlbuilder.model.Field;
import com.youngdatafan.sqlbuilder.model.Function;
import com.youngdatafan.sqlbuilder.model.Query;
import com.youngdatafan.sqlbuilder.model.Schema;
import com.youngdatafan.sqlbuilder.model.Table;

public class Test {

    @org.junit.Test
    public void function() {
        Schema schema = Schema.getSchema("");
        Table test = Table.getOriginalTable(schema, "test", "t");
        Query query = new Query();
        query.addFrom(test);
        Field age = test.addField("age");
        Function function = Function.getFunction(FunctionType.STANDARD_ERROR, age);
        query.addColumn(function);
        System.out.println("oracle：");
        System.out.println(query.getDatabaseSql(DatabaseType.ORACLE));
        System.out.println();

        System.out.println("pg：");
        System.out.println(query.getDatabaseSql(DatabaseType.POSTGRESQL));
        System.out.println();

        System.out.println("clickhouse：");
        System.out.println(query.getDatabaseSql(DatabaseType.CLICKHOUSE));
        System.out.println();

        System.out.println("mysql：");
        System.out.println(query.getDatabaseSql(DatabaseType.MYSQL));
        System.out.println();

        System.out.println("sqlserver：");
        System.out.println(query.getDatabaseSql(DatabaseType.MSSQL));
        System.out.println();

        System.out.println("kdw：");
        System.out.println(query.getDatabaseSql(DatabaseType.KDW));
        System.out.println();
    }
}

根据数据源获取对于数据库的sql。

ORACLE​

SELECT STDDEV_SAMP(t."age")/SQRT(count(1)) FROM "test" t

MYSQL​

SELECT STDDEV_SAMP(t.`age`)/SQRT(count(1)) FROM `test` t

POSTGRESQL​

SELECT STDDEV_SAMP(t.age)/SQRT(count(1)) FROM test t

CLICKHOUSE​

SELECT if(COUNT(1) = 0, null, stddevSamp(t.age)/SQRT(count(1))) FROM test t

KDW​

SELECT STDDEV_SAMP(t.age)/SQRT(count(1)) FROM test t

SQLSERVER​

SELECT STDEV(t.age)/SQRT(count(1)) FROM test t