将另一个 table 导入数据库并添加字段
Importing another table into a database and adding fields
我有一个 csv 文件，我想将其导入到我的数据库中。但是，csv 文件中的列与我要将其导入的 table 中的列不匹配。我想做两件事：
- 导入 table 但仅导入部分列
- 为我正在导入的 table 没有的列提供默认值。
我希望我解释得足够好。不太确定如何为这个问题添加任何 'code'，但我已经放入了一些图片。
这是我现有的 table:
这是我要导入的 csv 文件的列
我想以某种方式只将此 csv 文件的名称（作为标题）、slug 和 created_at、updated_at 导入我的 table。此外，我希望自动添加 ID，并将 'exam_id' 和 'popular' 布尔值默认设置为 0。
LOAD DATA INFILE 就是您所需要的。
仔细阅读：http://dev.mysql.com/doc/refman/5.7/en/load-data.html.
您最感兴趣的部分是：
By default, when no column list is provided at the end of the LOAD
DATA INFILE statement, input lines are expected to contain a field for
each table column. If you want to load only some of a table's columns,
specify a column list:
LOAD DATA INFILE 'persondata.txt' INTO TABLE persondata
(col1,col2,...);
You must also specify a column list if the order of the fields in the
input file differs from the order of the columns in the table.
Otherwise, MySQL cannot tell how to match input fields with table
columns.
The column list can contain either column names or user variables.
With user variables, the SET clause enables you to perform
transformations on their values before assigning the result to
columns.
User variables in the SET clause can be used in several ways. The
following example uses the first input column directly for the value
of t1.column1, and assigns the second input column to a user variable
that is subjected to a division operation before being used for the
value of t1.column2:
LOAD DATA INFILE 'file.txt' INTO TABLE t1 (column1, @var1) SET
column2 = @var1/100;
The SET clause can be used to supply values not derived from the input
file. The following statement sets column3 to the current date and
time:
LOAD DATA INFILE 'file.txt' INTO TABLE t1 (column1, column2) SET
column3 = CURRENT_TIMESTAMP;
You can also discard an input value by assigning it to a user variable
and not assigning the variable to a table column:
LOAD DATA INFILE 'file.txt' INTO TABLE t1 (column1, @dummy,
column2, @dummy, column3);
我有一个 csv 文件，我想将其导入到我的数据库中。但是，csv 文件中的列与我要将其导入的 table 中的列不匹配。我想做两件事：
- 导入 table 但仅导入部分列
- 为我正在导入的 table 没有的列提供默认值。
我希望我解释得足够好。不太确定如何为这个问题添加任何 'code'，但我已经放入了一些图片。
这是我现有的 table:
这是我要导入的 csv 文件的列
我想以某种方式只将此 csv 文件的名称（作为标题）、slug 和 created_at、updated_at 导入我的 table。此外，我希望自动添加 ID，并将 'exam_id' 和 'popular' 布尔值默认设置为 0。
LOAD DATA INFILE 就是您所需要的。
仔细阅读：http://dev.mysql.com/doc/refman/5.7/en/load-data.html.
您最感兴趣的部分是：
By default, when no column list is provided at the end of the LOAD DATA INFILE statement, input lines are expected to contain a field for each table column. If you want to load only some of a table's columns, specify a column list:
LOAD DATA INFILE 'persondata.txt' INTO TABLE persondata
(col1,col2,...);
You must also specify a column list if the order of the fields in the input file differs from the order of the columns in the table. Otherwise, MySQL cannot tell how to match input fields with table columns.
The column list can contain either column names or user variables. With user variables, the SET clause enables you to perform transformations on their values before assigning the result to columns.
User variables in the SET clause can be used in several ways. The following example uses the first input column directly for the value of t1.column1, and assigns the second input column to a user variable that is subjected to a division operation before being used for the value of t1.column2:
LOAD DATA INFILE 'file.txt' INTO TABLE t1 (column1, @var1) SET
column2 = @var1/100;
The SET clause can be used to supply values not derived from the input file. The following statement sets column3 to the current date and time:
LOAD DATA INFILE 'file.txt' INTO TABLE t1 (column1, column2) SET
column3 = CURRENT_TIMESTAMP;
You can also discard an input value by assigning it to a user variable and not assigning the variable to a table column:
LOAD DATA INFILE 'file.txt' INTO TABLE t1 (column1, @dummy,
column2, @dummy, column3);