Import a `.del` file (a delimited file, exported from DB2) into SQLite

It is possible to import a .del file (a delimited file, such as one exported from DB2) into SQLite, but you might need to process the file depending on its format. SQLite supports importing data from CSV files, so the key is to convert your .del file into a format SQLite can understand, such as a standard CSV.

Steps to Import DB2 `.del` File into SQLite:

Inspect the .del File Format:
- Check the delimiter used in the .del file (commonly |, \t, or another character).
- Verify if the file includes a header row with column names.
- Look for any special encoding or escape characters.
Convert .del to CSV:
- If the .del file uses a delimiter other than a comma (,), replace the delimiter with a comma. You can use tools like sed, awk, or Python scripts.
- Example using sed (assuming | as the delimiter):
  bash 复制代码
```
sed 's/|/,/g' T_db_table.del > T_db_table.csv
```
- Ensure all fields are properly quoted if necessary (e.g., strings with commas).
Create the SQLite Table:
- Manually define the schema in SQLite to match the structure of your .del file.
- Example:
  sql 复制代码
```
CREATE TABLE T_db_table (
    column1 TEXT,
    column2 INTEGER,
    column3 REAL
    -- Add more columns as needed
);
```
Import the Converted File into SQLite:
- Use the .import command in the SQLite CLI:
  bash 复制代码
```
sqlite3 your_database.db
.mode csv
.import T_db_table.csv T_db_table
```
- If the file has a header row, SQLite will skip it automatically. If it doesn't, ensure the .csv file matches the order of columns in your table.
Verify the Data:
- Query the table to ensure the data was imported correctly:
  sql 复制代码
```
SELECT * FROM T_db_table LIMIT 10;
```
Automate if Necessary:
- If you have multiple files, write a script to automate the conversion and import process.

Considerations for Migration to ARM Environment:

Data Validation: Ensure the data types in SQLite align with the original DB2 schema to avoid truncation or conversion errors.
Encoding : Confirm the .del file encoding (e.g., UTF-8) matches the expected encoding for SQLite.
Index and Constraints: Recreate any indexes or constraints from DB2 in SQLite for testing purposes.

When migrating from DB2 to SQLite, column types don't have a one-to-one match because the systems have different type systems. However, I can provide a general mapping guide based on common DB2 types and their closest equivalents in SQLite.

General Column Type Mapping from DB2 to SQLite:

DB2 Type	SQLite Type	Explanation
`CHAR(n)`	`TEXT`	`CHAR(n)` is a fixed-length string in DB2. SQLite stores it as a variable-length string (`TEXT`).
`VARCHAR(n)`	`TEXT`	`VARCHAR(n)` is a variable-length string, similar to `TEXT` in SQLite.
`CLOB`	`TEXT`	`CLOB` (Character Large Object) in DB2 is treated as `TEXT` in SQLite.
`INTEGER`	`INTEGER`	Both DB2 and SQLite use `INTEGER` for integers.
`BIGINT`	`INTEGER`	SQLite stores large integers as `INTEGER`.
`DECIMAL(p, s)`	`REAL`	`DECIMAL` is stored as a floating-point number (`REAL`) in SQLite.
`NUMERIC(p, s)`	`REAL`	`NUMERIC` in DB2 is typically mapped to `REAL` in SQLite.
`FLOAT`, `DOUBLE`	`REAL`	Both `FLOAT` and `DOUBLE` are mapped to `REAL` in SQLite.
`DATE`	`TEXT`	SQLite stores dates as `TEXT` in the ISO 8601 format (`YYYY-MM-DD`).
`TIME`	`TEXT`	`TIME` is also stored as `TEXT` in SQLite (`HH:MM:SS`).
`TIMESTAMP`	`TEXT`	`TIMESTAMP` in DB2 is stored as `TEXT` in SQLite (`YYYY-MM-DD HH:MM:SS`).
`BINARY(n)`	`BLOB`	`BINARY` is mapped to `BLOB` (Binary Large Object) in SQLite.
`VARBINARY(n)`	`BLOB`	`VARBINARY` is also mapped to `BLOB` in SQLite.
`BOOLEAN`	`INTEGER`	SQLite uses `INTEGER` for boolean values, where `0` is false and `1` is true.

Example Mapping for Your Table:

If your DB2 table includes columns like CHAR(2) or VARCHAR(512), you could map them to TEXT in SQLite, as both types store strings.

For instance:

CHAR(2) in DB2 → TEXT in SQLite (Fixed-length string)
VARCHAR(512) in DB2 → TEXT in SQLite (Variable-length string)

Example DB2 to SQLite Mapping:

If you have a DB2 table like this:

sql 复制代码

CREATE TABLE T_db_table(
    column1 CHAR(2),      -- Fixed-length string
    column2 VARCHAR(512), -- Variable-length string
    column3 DECIMAL(10,2),-- Decimal number
    column4 INTEGER,      -- Integer
    column5 DATE          -- Date
);

You could map it to SQLite like this:

sql 复制代码

CREATE TABLE T_db_table (
    column1 TEXT,         -- CHAR(2) mapped to TEXT
    column2 TEXT,         -- VARCHAR(512) mapped to TEXT
    column3 REAL,         -- DECIMAL(10,2) mapped to REAL
    column4 INTEGER,      -- INTEGER stays INTEGER
    column5 TEXT          -- DATE mapped to TEXT (ISO format)
);

Some Additional Considerations:

Precision : If you are working with DECIMAL or NUMERIC types in DB2 with specified precision and scale, SQLite doesn't enforce the precision, so it treats them as REAL. This can result in rounding or precision issues if you need high precision.
Date/Time: SQLite stores date and time values as text in ISO 8601 format, which is a string representation. Make sure you format the date/time correctly before importing if it's not already in that format.
String Length : In SQLite, TEXT columns are flexible and don't have a length constraint (unlike CHAR(n) or VARCHAR(n) in DB2). So, there's no need to worry about setting a column length in SQLite.

UPDATE t_db_table SET custtype=TRIM(custtype), TYPE=TRIM(type);

Makefile

bash 复制代码

CC = gcc
CFLAGS = -Wall -g
LDFLAGS = -lsqlite3
TARGET = sqlite_query_demo

all: $(TARGET)

$(TARGET): sqlite_query_demo.c
	$(CC) $(CFLAGS) -o $(TARGET) sqlite_query_demo.c $(LDFLAGS)

clean:
	rm -f $(TARGET) *.o

// sqlite_query_demo.c

c 复制代码

#include <stdio.h>
#include <stdlib.h>
#include <sqlite3.h>

void execute_query(sqlite3 *db, const char *custno, const char *type) {
    const char *sql_template = "SELECT * FROM T_db_table WHERE custtype='1' AND custno=? AND type=?";
    sqlite3_stmt *stmt;
    int rc;

    // Prepare the SQL statement
    rc = sqlite3_prepare_v2(db, sql_template, -1, &stmt, NULL);
    if (rc != SQLITE_OK) {
        fprintf(stderr, "Failed to prepare statement: %s\n", sqlite3_errmsg(db));
        return;
    }

    // Bind the parameters
    sqlite3_bind_text(stmt, 1, custno, -1, SQLITE_STATIC);
    sqlite3_bind_text(stmt, 2, type, -1, SQLITE_STATIC);

    // Execute the query and print the results
    printf("Results:\n");
    while ((rc = sqlite3_step(stmt)) == SQLITE_ROW) {
        int columns = sqlite3_column_count(stmt);
        for (int i = 0; i < columns; i++) {
            printf("%s = %s\t", sqlite3_column_name(stmt, i), sqlite3_column_text(stmt, i));
        }
        printf("\n");
    }

    if (rc != SQLITE_DONE) {
        fprintf(stderr, "Error while executing statement: %s\n", sqlite3_errmsg(db));
    }

    // Finalize the statement
    sqlite3_finalize(stmt);
}

int main(int argc, char *argv[]) {
    if (argc != 4) {
        fprintf(stderr, "Usage: %s <database> <custno> <type>\n", argv[0]);
        return EXIT_FAILURE;
    }

    const char *db_path = argv[1];
    const char *custno = argv[2];
    const char *type = argv[3];

    sqlite3 *db;
    int rc;

    // Open the database
    rc = sqlite3_open(db_path, &db);
    if (rc) {
        fprintf(stderr, "Can't open database: %s\n", sqlite3_errmsg(db));
        return EXIT_FAILURE;
    }

    execute_query(db, custno, type);

    // Close the database
    sqlite3_close(db);

    return EXIT_SUCCESS;
}