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SQLite training in Houston TX on 2019-11-05 (details)
Part of the 2019 Tcl Conference

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Overview
Comment:In the CLI, code the "sqlite_parameters" name directly rather than using a macro, for clarity of presentation for users who are reading the code for the purpose of seeing how the CLI implements parameter binding.
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SHA3-256: e775ef002dd33e6bcbeec8d4b6ad7f59749e35548c7a59c9fa3bcfdc5cc50730
User & Date: drh 2019-03-25 21:56:26
Context
2019-03-25
22:05
Fix an obsolete comment in the CLI. No code changes. check-in: fade103c user: drh tags: trunk
21:56
In the CLI, code the "sqlite_parameters" name directly rather than using a macro, for clarity of presentation for users who are reading the code for the purpose of seeing how the CLI implements parameter binding. check-in: e775ef00 user: drh tags: trunk
21:55
Remove a test from the index build logic which is no longer needed and is in fact unreachable. check-in: 9b20ee10 user: drh tags: trunk
Changes
Hide Diffs Unified Diffs Ignore Whitespace Patch

Changes to src/shell.c.in.

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  sqlite3SelectTrace = savedSelectTrace;
#endif
#if defined(SQLITE_DEBUG) && defined(SQLITE_ENABLE_WHERETRACE)
  sqlite3WhereTrace = savedWhereTrace;
#endif
}

/* Name of the TEMP table that holds bind parameter values */
#define BIND_PARAM_TABLE "sqlite_parameters"

/* Create the TEMP table used to store parameter bindings */
static void bind_table_init(ShellState *p){
  int wrSchema = 0;
  sqlite3_db_config(p->db, SQLITE_DBCONFIG_WRITABLE_SCHEMA, -1, &wrSchema);
  sqlite3_db_config(p->db, SQLITE_DBCONFIG_WRITABLE_SCHEMA, 1, 0);
  sqlite3_exec(p->db,
    "CREATE TABLE IF NOT EXISTS temp." BIND_PARAM_TABLE "(\n"
    "  key TEXT PRIMARY KEY,\n"
    "  value ANY\n"
    ") WITHOUT ROWID;",
    0, 0, 0);
  sqlite3_db_config(p->db, SQLITE_DBCONFIG_WRITABLE_SCHEMA, wrSchema, 0);
}

................................................................................
  int nVar;
  int i;
  int rc;
  sqlite3_stmt *pQ = 0;

  nVar = sqlite3_bind_parameter_count(pStmt);
  if( nVar==0 ) return;  /* Nothing to do */
  if( sqlite3_table_column_metadata(pArg->db, "TEMP", BIND_PARAM_TABLE,
                                    "key", 0, 0, 0, 0, 0)!=SQLITE_OK ){
    return; /* Parameter table does not exist */
  }
  rc = sqlite3_prepare_v2(pArg->db,
          "SELECT value FROM temp." BIND_PARAM_TABLE
          " WHERE key=?1", -1, &pQ, 0);
  if( rc || pQ==0 ) return;
  for(i=1; i<=nVar; i++){
    char zNum[30];
    const char *zVar = sqlite3_bind_parameter_name(pStmt, i);
    if( zVar==0 ){
      sqlite3_snprintf(sizeof(zNum),zNum,"?%d",i);
................................................................................
    /* .parameter clear
    ** Clear all bind parameters by dropping the TEMP table that holds them.
    */
    if( nArg==2 && strcmp(azArg[1],"clear")==0 ){
      int wrSchema = 0;
      sqlite3_db_config(p->db, SQLITE_DBCONFIG_WRITABLE_SCHEMA, -1, &wrSchema);
      sqlite3_db_config(p->db, SQLITE_DBCONFIG_WRITABLE_SCHEMA, 1, 0);
      sqlite3_exec(p->db, "DROP TABLE IF EXISTS temp." BIND_PARAM_TABLE ";",
                   0, 0, 0);
      sqlite3_db_config(p->db, SQLITE_DBCONFIG_WRITABLE_SCHEMA, wrSchema, 0);
    }else

    /* .parameter list
    ** List all bind parameters.
    */
    if( nArg==2 && strcmp(azArg[1],"list")==0 ){
      sqlite3_stmt *pStmt = 0;
      int rx;
      int len = 0;
      rx = sqlite3_prepare_v2(p->db,
             "SELECT max(length(key)) "
             "FROM temp." BIND_PARAM_TABLE ";", -1, &pStmt, 0);
      if( rx==SQLITE_OK && sqlite3_step(pStmt)==SQLITE_ROW ){
        len = sqlite3_column_int(pStmt, 0);
        if( len>40 ) len = 40;
      }
      sqlite3_finalize(pStmt);
      pStmt = 0;
      if( len ){
        rx = sqlite3_prepare_v2(p->db,
             "SELECT key, quote(value) "
             "FROM temp." BIND_PARAM_TABLE ";", -1, &pStmt, 0);
        while( sqlite3_step(pStmt)==SQLITE_ROW ){
          utf8_printf(p->out, "%-*s %s\n", len, sqlite3_column_text(pStmt,0),
                      sqlite3_column_text(pStmt,1));
        }
        sqlite3_finalize(pStmt);
      }
    }else
................................................................................
      int rx;
      char *zSql;
      sqlite3_stmt *pStmt;
      const char *zKey = azArg[2];
      const char *zValue = azArg[3];
      bind_table_init(p);
      zSql = sqlite3_mprintf(
                  "REPLACE INTO temp." BIND_PARAM_TABLE "(key,value)"
                  "VALUES(%Q,%s);", zKey, zValue);
      if( zSql==0 ) shell_out_of_memory();
      pStmt = 0;
      rx = sqlite3_prepare_v2(p->db, zSql, -1, &pStmt, 0);
      sqlite3_free(zSql);
      if( rx!=SQLITE_OK ){
        sqlite3_finalize(pStmt);
        pStmt = 0;
        zSql = sqlite3_mprintf(
                   "REPLACE INTO temp." BIND_PARAM_TABLE "(key,value)"
                   "VALUES(%Q,%Q);", zKey, zValue);
        if( zSql==0 ) shell_out_of_memory();
        rx = sqlite3_prepare_v2(p->db, zSql, -1, &pStmt, 0);
        sqlite3_free(zSql);
        if( rx!=SQLITE_OK ){
          utf8_printf(p->out, "Error: %s\n", sqlite3_errmsg(p->db));
          sqlite3_finalize(pStmt);
................................................................................

    /* .parameter unset NAME
    ** Remove the NAME binding from the parameter binding table, if it
    ** exists.
    */
    if( nArg==3 && strcmp(azArg[1],"unset")==0 ){
      char *zSql = sqlite3_mprintf(
          "DELETE FROM temp." BIND_PARAM_TABLE " WHERE key=%Q", azArg[2]);
      if( zSql==0 ) shell_out_of_memory();
      sqlite3_exec(p->db, zSql, 0, 0, 0);
      sqlite3_free(zSql);
    }else
    /* If no command name matches, show a syntax error */
    parameter_syntax_error:
    showHelp(p->out, "parameter");







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  sqlite3SelectTrace = savedSelectTrace;
#endif
#if defined(SQLITE_DEBUG) && defined(SQLITE_ENABLE_WHERETRACE)
  sqlite3WhereTrace = savedWhereTrace;
#endif
}




/* Create the TEMP table used to store parameter bindings */
static void bind_table_init(ShellState *p){
  int wrSchema = 0;
  sqlite3_db_config(p->db, SQLITE_DBCONFIG_WRITABLE_SCHEMA, -1, &wrSchema);
  sqlite3_db_config(p->db, SQLITE_DBCONFIG_WRITABLE_SCHEMA, 1, 0);
  sqlite3_exec(p->db,
    "CREATE TABLE IF NOT EXISTS temp.sqlite_parameters(\n"
    "  key TEXT PRIMARY KEY,\n"
    "  value ANY\n"
    ") WITHOUT ROWID;",
    0, 0, 0);
  sqlite3_db_config(p->db, SQLITE_DBCONFIG_WRITABLE_SCHEMA, wrSchema, 0);
}

................................................................................
  int nVar;
  int i;
  int rc;
  sqlite3_stmt *pQ = 0;

  nVar = sqlite3_bind_parameter_count(pStmt);
  if( nVar==0 ) return;  /* Nothing to do */
  if( sqlite3_table_column_metadata(pArg->db, "TEMP", "sqlite_parameters",
                                    "key", 0, 0, 0, 0, 0)!=SQLITE_OK ){
    return; /* Parameter table does not exist */
  }
  rc = sqlite3_prepare_v2(pArg->db,
          "SELECT value FROM temp.sqlite_parameters"
          " WHERE key=?1", -1, &pQ, 0);
  if( rc || pQ==0 ) return;
  for(i=1; i<=nVar; i++){
    char zNum[30];
    const char *zVar = sqlite3_bind_parameter_name(pStmt, i);
    if( zVar==0 ){
      sqlite3_snprintf(sizeof(zNum),zNum,"?%d",i);
................................................................................
    /* .parameter clear
    ** Clear all bind parameters by dropping the TEMP table that holds them.
    */
    if( nArg==2 && strcmp(azArg[1],"clear")==0 ){
      int wrSchema = 0;
      sqlite3_db_config(p->db, SQLITE_DBCONFIG_WRITABLE_SCHEMA, -1, &wrSchema);
      sqlite3_db_config(p->db, SQLITE_DBCONFIG_WRITABLE_SCHEMA, 1, 0);
      sqlite3_exec(p->db, "DROP TABLE IF EXISTS temp.sqlite_parameters;",
                   0, 0, 0);
      sqlite3_db_config(p->db, SQLITE_DBCONFIG_WRITABLE_SCHEMA, wrSchema, 0);
    }else

    /* .parameter list
    ** List all bind parameters.
    */
    if( nArg==2 && strcmp(azArg[1],"list")==0 ){
      sqlite3_stmt *pStmt = 0;
      int rx;
      int len = 0;
      rx = sqlite3_prepare_v2(p->db,
             "SELECT max(length(key)) "
             "FROM temp.sqlite_parameters;", -1, &pStmt, 0);
      if( rx==SQLITE_OK && sqlite3_step(pStmt)==SQLITE_ROW ){
        len = sqlite3_column_int(pStmt, 0);
        if( len>40 ) len = 40;
      }
      sqlite3_finalize(pStmt);
      pStmt = 0;
      if( len ){
        rx = sqlite3_prepare_v2(p->db,
             "SELECT key, quote(value) "
             "FROM temp.sqlite_parameters;", -1, &pStmt, 0);
        while( sqlite3_step(pStmt)==SQLITE_ROW ){
          utf8_printf(p->out, "%-*s %s\n", len, sqlite3_column_text(pStmt,0),
                      sqlite3_column_text(pStmt,1));
        }
        sqlite3_finalize(pStmt);
      }
    }else
................................................................................
      int rx;
      char *zSql;
      sqlite3_stmt *pStmt;
      const char *zKey = azArg[2];
      const char *zValue = azArg[3];
      bind_table_init(p);
      zSql = sqlite3_mprintf(
                  "REPLACE INTO temp.sqlite_parameters(key,value)"
                  "VALUES(%Q,%s);", zKey, zValue);
      if( zSql==0 ) shell_out_of_memory();
      pStmt = 0;
      rx = sqlite3_prepare_v2(p->db, zSql, -1, &pStmt, 0);
      sqlite3_free(zSql);
      if( rx!=SQLITE_OK ){
        sqlite3_finalize(pStmt);
        pStmt = 0;
        zSql = sqlite3_mprintf(
                   "REPLACE INTO temp.sqlite_parameters(key,value)"
                   "VALUES(%Q,%Q);", zKey, zValue);
        if( zSql==0 ) shell_out_of_memory();
        rx = sqlite3_prepare_v2(p->db, zSql, -1, &pStmt, 0);
        sqlite3_free(zSql);
        if( rx!=SQLITE_OK ){
          utf8_printf(p->out, "Error: %s\n", sqlite3_errmsg(p->db));
          sqlite3_finalize(pStmt);
................................................................................

    /* .parameter unset NAME
    ** Remove the NAME binding from the parameter binding table, if it
    ** exists.
    */
    if( nArg==3 && strcmp(azArg[1],"unset")==0 ){
      char *zSql = sqlite3_mprintf(
          "DELETE FROM temp.sqlite_parameters WHERE key=%Q", azArg[2]);
      if( zSql==0 ) shell_out_of_memory();
      sqlite3_exec(p->db, zSql, 0, 0, 0);
      sqlite3_free(zSql);
    }else
    /* If no command name matches, show a syntax error */
    parameter_syntax_error:
    showHelp(p->out, "parameter");