blocks|key|1102310|text|点命令仅对sqlite3可执行文件可用。您必须将它们替换为Python代码和DB-API调用的等效组合，以便模仿它们的行为。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1102311|entityMap^0|5|7|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|K|8|@]|D|@]|E|$]]]|G|$]]

The dot commands are only available to the <code>sqlite3</code> executable. You will have to replace them with the equivalent combination of Python code and DB-API calls in order to mimic their behavior.

blocks|key|1102362|text|您可以使用load_extension()内置的SQLite函数或SQLite命令行shell中的.load命令加载新的排序序列和函数。显然，扩展应该用C编写。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1102363|而且不能从python调用点命令，因为点命令特定于命令行shell工具。|1102364|entityMap|0|LINK|mutability|MUTABLE|url|http://sqlite.org/lang_corefunc.html#load_extension|1|http://sqlite.org/sqlite.html^0|5|G|0|1D|5|1|0|0^^$0|@$1|2|3|4|5|6|7|P|8|@]|9|@$A|Q|B|R|1|S]|$A|T|B|U|1|V]]|C|$]]|$1|D|3|E|5|6|7|W|8|@]|9|@]|C|$]]|$1|F|3|-4|5|6|7|X|8|@]|9|@]|C|$]]]|G|$H|$5|I|J|K|C|$L|M]]|N|$5|I|J|K|C|$L|O]]]]

You can load new collating sequences and functions using <a href="http://sqlite.org/lang_corefunc.html#load_extension" rel="noreferrer">load_extension()</a> built-in SQLite function or <a href="http://sqlite.org/sqlite.html" rel="noreferrer">.load</a> command in command line shell for SQLite. Obviously, extensions shold be written in C.

And you can not call dot-commands from python, because dot-commands are specific to the command line shell tool.

blocks|key|1102430|text|sqlite+shell中的.import命令是一个内置命令。它是由shell程序处理的，而不是SQL引擎，所以您不能像SQL语句那样执行它。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1102431|在读取SQLite的shell.c代码时，.import似乎只是一个循环，从数据文件中读取行，拆分分隔符，并将字段作为参数值传递给准备好的INSERT语句。因此，您应该能够很容易地用Python代码模拟.import的行为。|1102432|我用Python+2.6测试了以下内容：|1102433|import+sqlite3
import+csv

conn+=+sqlite3.connect(':memory:')

conn.execute('create+table+mytable+(col1+text,+col2+text,+col3+text)')

csvReader+=+csv.reader(open('mydata.csv'),+delimiter=',',+quotechar='"')

for+row+in+csvReader:
++++++++conn.execute('insert+into+mytable+(col1,+col2,+col3)+values+(?,+?,+?)',+row)

cur+=+conn.cursor()
cur.execute('select+*+from+mytable')
print+cur.fetchall()|code-block|syntax|javascript|1102434|entityMap|0|LINK|mutability|MUTABLE|url|http://www.sqlite.org/src/finfo?name=src/shell.c^0|E|7|0|L|7|1X|6|2T|7|A|7|0|0|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@$9|X|A|Y|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|Z|8|@$9|10|A|11|B|C]|$9|12|A|13|B|C]|$9|14|A|15|B|C]]|D|@$9|16|A|17|1|18]]|E|$]]|$1|H|3|I|5|6|7|19|8|@]|D|@]|E|$]]|$1|J|3|K|5|L|7|1A|8|@]|D|@]|E|$M|N]]|$1|O|3|-4|5|6|7|1B|8|@]|D|@]|E|$]]]|P|$Q|$5|R|S|T|E|$U|V]]]]

The <code>.import</code> command in the sqlite shell is a builtin command. It's processed by the shell program, not the SQL engine, so you can't execute it like an SQL statement.

Reading code for SQLite's <a href="http://www.sqlite.org/src/finfo?name=src/shell.c" rel="noreferrer">shell.c</a>, it seems that <code>.import</code> is simply a loop, reading lines from the data file, splitting on the separator, and passing the fields as parameter values to a prepared <code>INSERT</code> statement. So you should be able to mimic the behavior of <code>.import</code> with Python code easily.

I tested the following with Python 2.6:

<pre><code>import sqlite3
import csv

conn = sqlite3.connect(':memory:')

conn.execute('create table mytable (col1 text, col2 text, col3 text)')

csvReader = csv.reader(open('mydata.csv'), delimiter=',', quotechar='"')

for row in csvReader:
 conn.execute('insert into mytable (col1, col2, col3) values (?, ?, ?)', row)

cur = conn.cursor()
cur.execute('select * from mytable')
print cur.fetchall()
</code></pre>

blocks|key|1102496|text|您可以使用子进程模块从Python调用点命令，这基本上调用了一个shell。如果需要使用多个点命令，可以将它们作为单独的shell参数传递--使用分号分隔它们是行不通的。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1102497|import+subprocess
subprocess.call(["sqlite3",+"xxx.db",+
++".mode+tabs",+
++".import+file.tsv+table_name"])|code-block|syntax|javascript|1102498|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

You can call dot commands from Python using the subprocess module, which basically invokes a shell. If you need to use multiple dot commands, you can pass them as separate shell arguments - using a semicolon to separate them won't work.

<pre><code>import subprocess
subprocess.call(["sqlite3", "xxx.db", 
 ".mode tabs", 
 ".import file.tsv table_name"])
</code></pre>

blocks|key|1317465|text|与subprocess.call()相比，subprocess.run()更受欢迎。以下是我的答案：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1317466|import+subprocess
schema+=+subprocess.run(
++++['sqlite3',
+++++'xxx.db',
+++++'.schema'
++++],
++++capture_output=True
).output.decode('utf-8')

print(schema)|code-block|syntax|javascript|1317467|entityMap^0|1|H|L|G|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]|$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|R|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|S|8|@]|D|@]|E|$]]]|L|$]]

<code>subprocess.run()</code> is preferred over<code>subprocess.call()</code>. Below is my answer:

<pre><code>import subprocess
schema = subprocess.run(
 ['sqlite3',
 'xxx.db',
 '.schema'
 ],
 capture_output=True
).output.decode('utf-8')

print(schema)
</code></pre>

My sqlite3 database contains a "collate" column-constraint. I've placed it in the schema for the table, to prevent accidentally neglecting to use the necessary collation. However this means when running <code>sqlite3</code> from the command line, and not from my Python code, the collation referenced in the schema is not present, and I'm unable to use dot commands.

<pre><code>sqlite&gt; .import data.txt table_name
Error: no such collation sequence: my_collation
</code></pre>

Furthermore, creating the connection from Python, and adding the collation required runs into this problem:

<pre><code>connWithCollation.execute(".import data.txt table_name")
Traceback (most recent call last):
 File "&lt;stdin&gt;", line 1, in &lt;module&gt;
sqlite3.OperationalError: near ".": syntax error
</code></pre>

The <code>execute</code> function it would appear does not want to pass the sqlite3 dot command through.

How can I execute sqlite3 dot commands when necessary collation functions are not present? Alternatively, how can I execute sqlite3 dot commands from Python?

Execute sqlite3 "dot" commands from Python or register collation in command line utility

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我的sqlite3数据库包含一个"collate“列约束。我已经将它放在表的模式中，以防止意外疏忽使用必要的排序规则。然而，这意味着当从命令行运行sqlite3时，而不是从我的Python代码运行时，模式中引用的排序规则不存在，并且我无法使用点命令。sqlite> .import data.txt table_name...

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