補虛日期爲NULL SQL查詢

我有一個CSV文件，該文件是這樣的：補虛日期爲NULL SQL查詢

Dates Experiment Experiment_Type RESET_FREQUENCY MEASURE_LENGTH Value Date_Integer 
2016-09-28 A FORWARD_Detector 1 Minute 1 0.99994 20160928 
      A FORWARD_Detector 1 Minute 7 0.99959 20160928 
2016-09-28 A FORWARD_Detector 1 Minute 14 0.99917 20160928 
2016-09-28 A FORWARD_Detector 1 Minute 21 0.99876 20160928 
      A FORWARD_Detector 1 Minute 30 0.99823 20160928

我收到如下：

Dates Experiment Experiment_Type RESET_FREQUENCY MEASURE_LENGTH Value Date_Integer 
2016-09-28 A FORWARD_Detector 1 Minute 1 0.99994 20160928 
0000-00-00 A FORWARD_Detector 1 Minute 7 0.99959 20160928 
2016-09-28 A FORWARD_Detector 1 Minute 14 0.99917 20160928 
2016-09-28 A FORWARD_Detector 1 Minute 21 0.99876 20160928 
0000-00-00 A FORWARD_Detector 1 Minute 30 0.99823 20160928

但我想要的是：

Dates Experiment Experiment_Type RESET_FREQUENCY MEASURE_LENGTH Value Date_Integer 
2016-09-28 A FORWARD_Detector 1 Minute 1 0.99994 20160928 
NULL  A FORWARD_Detector 1 Minute 7 0.99959 20160928 
2016-09-28 A FORWARD_Detector 1 Minute 14 0.99917 20160928 
2016-09-28 A FORWARD_Detector 1 Minute 21 0.99876 20160928 
NULL  A FORWARD_Detector 1 Minute 30 0.99823 20160928

我的查詢如下所示：

exp_data = """LOAD DATA LOCAL INFILE 'C:/Data.csv' IGNORE 
    INTO TABLE interest_rate_curves_bootstrap 
    FIELDS TERMINATED BY ';' 
    LINES TERMINATED BY "\\n" 
    (@var1,Experiment,Experiment_Type,RESET_FREQUENCY,MEASURE_LENGTH Value, Date_Integer) 
    set Dates = STR_TO_DATE(@var1, '%d-%b-%y');"""

我嘗試以下，但並沒有奏效：

ALTER TABLE experiment_US MODIFY COLUMN experiment_data DATETIME NULL;

，然後更新值：

UPDATE experiment_USSET experiment_data= NULL WHERE experiment_data= '0000-00-00'; 

import sqlalchemy as sqlal 

#connection to mysql database 
mysql_engine = sqlal.create_engine('mysql+mysqlconnector://[email protected]/rates data') 


mysql_engine.raw_connection() 

metadata = sqlal.MetaData() 

experiment_data = sqlal.Table('experiment_data', metadata, 
              sqlal.Column('Date_String', sqlal.Date(), nullable=True), 
              sqlal.Column('Experiment', sqlal.String(3), nullable=True), 
              sqlal.Column('Experiment_Type', sqlal.String(8), nullable=True), 
              sqlal.Column('RESET_FREQUENCY', sqlal.String(3), nullable=True), 
              sqlal.Column('MEASURE_LENGHT', sqlal.Integer(), nullable=True), 
              sqlal.Column('Value', sqlal.Float(), nullable=True), 
              sqlal.Column('Date_Integer', sqlal.Integer(), nullable=True) 
              ) 

exp_data = """LOAD DATA LOCAL INFILE 'C:/Data.csv' IGNORE INTO TABLE experiment_data FIELDS TERMINATED BY ';' LINES TERMINATED BY "\\n" (@var1,Experiment,Experiment_Type,RESET_FREQUENCY,MEASURE_LENGTH Value, Date_Integer) set Dates = STR_TO_DATE(@var1, '%d-%b-%y');""" 

mysql_engine.execute(exp_data)

來源

2017-09-26 JonDoe

爲什麼你的查詢會說'FIELDS TERMINATED by';'？ CSV文件中沒有';'。 – Barmar

更改最後一行：

SET Dates = IF(@var1 = '', NULL, STR_TO_DATE(@var1, '%d-%b-%y'));"""

這用來檢查CSV字段爲空，然後將NULL放入表格中，而不是調用STR_TO_DATE 。

來源

2017-09-26 21:25:22 Barmar

非常感謝。那就是我一直在尋找的:)。 – JonDoe

補虛日期爲NULL SQL查詢

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