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query_rows.go
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/
query_rows.go
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// Licensed to ClickHouse, Inc. under one or more contributor
// license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright
// ownership. ClickHouse, Inc. licenses this file to you under
// the Apache License, Version 2.0 (the "License"); you may
// not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied. See the License for the
// specific language governing permissions and limitations
// under the License.
package clickhouse_api
import (
"context"
"fmt"
"time"
)
func QueryRows() error {
conn, err := GetNativeConnection(nil, nil, nil)
if err != nil {
return err
}
ctx := context.Background()
defer func() {
conn.Exec(ctx, "DROP TABLE example")
}()
if err := conn.Exec(ctx, `DROP TABLE IF EXISTS example`); err != nil {
return err
}
err = conn.Exec(ctx, `
CREATE TABLE IF NOT EXISTS example (
Col1 UInt8,
Col2 String,
Col3 DateTime
) engine=Memory
`)
if err != nil {
return err
}
batch, err := conn.PrepareBatch(ctx, "INSERT INTO example (Col1, Col2, Col3)")
if err != nil {
return err
}
for i := 0; i < 10; i++ {
if err := batch.Append(uint8(i), fmt.Sprintf("value_%d", i), time.Now()); err != nil {
return err
}
}
if err := batch.Send(); err != nil {
return err
}
rows, err := conn.Query(ctx, "SELECT Col1, Col2, Col3 FROM example WHERE Col1 >= 2")
if err != nil {
return err
}
for rows.Next() {
var (
col1 uint8
col2 string
col3 time.Time
)
if err := rows.Scan(&col1, &col2, &col3); err != nil {
return err
}
fmt.Printf("row: col1=%d, col2=%s, col3=%s\n", col1, col2, col3)
}
rows.Close()
return rows.Err()
}