SQLite modify column type

brief introduction

sqlite Cannot modify column type directly , So you need to create a temporary table , First copy the data into the temporary table , Then create a new table , Then copy the data of the temporary table back .

Example

--  Create a temporary table  sqlitestudio_temp_table, And with the table  learn_info  The data and structure are consistent 
CREATE TABLE sqlitestudio_temp_table AS SELECT * FROM learn_info;
--  Delete the original table 
DROP TABLE learn_info;
--  new table , The new instruction has modified the data type of the column 
CREATE TABLE learn_info (
    id            INTEGER PRIMARY KEY AUTOINCREMENT,
    type          INT,
    thought       TEXT,
    book          INT,
    chapter       INT,
    section       INT,
    number        TEXT,
    repeat        INT     DEFAULT 1,
    failed_repeat INT     DEFAULT 0,
    star          INT,
    comment       TEXT,
    span          INT,
    update_time   DATE    DEFAULT (datetime('now', 'localtime') ),
    version       INT,
    deleted       INT
);
--  Insert the data of the temporary table into the new table , If the modified field cannot be inserted , You can get rid of that column 
INSERT INTO learn_info (
                           id,
                           type,
                           thought,
                           book,
                           chapter,
                           section,
                           number,
                           repeat,
                           failed_repeat,
                           star,
                           comment,
                           span,
                           update_time,
                           version,
                           deleted
                       )
                       SELECT id,
                              type,
                              thought,
                              book,
                              chapter,
                              section,
                              number,
                              repeat,
                              failed_repeat,
                              star,
                              comment,
                              span,
                              update_time,
                              version,
                              deleted
                         FROM sqlitestudio_temp_table;
--  Delete temporary table 
DROP TABLE sqlitestudio_temp_table;