我有一个日期时间类型的列，我只想从中检索日期。有没有办法做到这一点？
以前它是一个纪元值，我将其转换为 datetime 。
这是一个示例结果：
smbd|ip address|1082|ip address|"2011-04-26 18:40:34"
我尝试了以下命令，但结果为负/零
SELECT DATE(datetime) from attacked_total;
SELECT STRFTIME('%Y-%m-%d', datetime) FROM attacked_total;
SELECT DATETIME('%Y-%m-%d', datetime) FROM attacked_total;
SELECT DATE('%Y-%m-%d', datetime) FROM attacked_total;
【问题讨论】：
您可以使用DATE 函数。
例子
> select date('2011-04-26 18:40:34')
> 2011-04-26
你只能用 strftime 得到一天，
> select strftime('%d', '2011-04-26 18:40:34')
> 26
【讨论】：
date(datetime)
这行得通。
SELECT strftime('%d', '2011-04-26')
您可以获得年、月、日以及日期中包含的所有其他内容。
但是你必须小心你如何输入这些字符串。
日期的格式是YYYY-MM-DD，所以你必须输入那个格式的字符串。
它也区分大小写。如果你想要一个月，那么你应该使用%m，因为如果你使用%M，它会尝试获取分钟，如果你的日期中没有时间部分，它会抛出错误。
更多信息请查看SQLite official site。
【讨论】：
如果您使用 SQLite，请尝试使用此功能
strftime('%Y', current_date)
strftime('%m', current_date)
strftime('%d', current_date)
strftime('%H', current_date)
strftime('%M', current_date)
strftime('%S', current_date)
如果您使用 Hibernate，请尝试在 SQLiteDialect 类中注册此函数
registerFunction("year", new SQLFunctionTemplate(StandardBasicTypes.INTEGER, "abs(strftime('%Y', ?1))"));
registerFunction("month", new SQLFunctionTemplate(StandardBasicTypes.INTEGER, "abs(strftime(strftime('%m', ?1))"));
registerFunction("day", new SQLFunctionTemplate(StandardBasicTypes.INTEGER, "abs(strftime(strftime('%d', ?1))"));
registerFunction("hour", new SQLFunctionTemplate(StandardBasicTypes.INTEGER, "abs(strftime(strftime('%H', ?1))"));
registerFunction("minute", new SQLFunctionTemplate(StandardBasicTypes.INTEGER, "abs(strftime(strftime('%M', ?1))"));
registerFunction("second", new SQLFunctionTemplate(StandardBasicTypes.INTEGER, "abs(strftime(strftime('%S', ?1))"));
如果你想提出任何建议，我会离开我的 SQLiteDialect 课程
import java.sql.SQLException;
import java.sql.Types;
import org.hibernate.JDBCException;
import org.hibernate.ScrollMode;
import org.hibernate.dialect.Dialect;
import org.hibernate.dialect.function.AbstractAnsiTrimEmulationFunction;
import org.hibernate.dialect.function.NoArgSQLFunction;
import org.hibernate.dialect.function.SQLFunction;
import org.hibernate.dialect.function.SQLFunctionTemplate;
import org.hibernate.dialect.function.StandardSQLFunction;
import org.hibernate.dialect.function.VarArgsSQLFunction;
import org.hibernate.dialect.identity.IdentityColumnSupport;
import utiles.SQLiteDialectIdentityColumnSupport;
import org.hibernate.dialect.pagination.AbstractLimitHandler;
import org.hibernate.dialect.pagination.LimitHandler;
import org.hibernate.dialect.pagination.LimitHelper;
import org.hibernate.dialect.unique.DefaultUniqueDelegate;
import org.hibernate.dialect.unique.UniqueDelegate;
import org.hibernate.engine.spi.RowSelection;
import org.hibernate.exception.DataException;
import org.hibernate.exception.JDBCConnectionException;
import org.hibernate.exception.LockAcquisitionException;
import org.hibernate.exception.spi.SQLExceptionConversionDelegate;
import org.hibernate.exception.spi.TemplatedViolatedConstraintNameExtracter;
import org.hibernate.exception.spi.ViolatedConstraintNameExtracter;
import org.hibernate.internal.util.JdbcExceptionHelper;
import org.hibernate.mapping.Column;
import org.hibernate.type.StandardBasicTypes;
/**
* An SQL dialect for SQLite 3.
*/
public class SQLiteDialect5 extends Dialect {
private final UniqueDelegate uniqueDelegate;
public SQLiteDialect5() {
registerColumnType(Types.BIT, "boolean");
//registerColumnType(Types.FLOAT, "float");
//registerColumnType(Types.DOUBLE, "double");
registerColumnType(Types.DECIMAL, "decimal");
registerColumnType(Types.CHAR, "char");
registerColumnType(Types.LONGVARCHAR, "longvarchar");
registerColumnType(Types.TIMESTAMP, "datetime");
registerColumnType(Types.BINARY, "blob");
registerColumnType(Types.VARBINARY, "blob");
registerColumnType(Types.LONGVARBINARY, "blob");
registerFunction("concat", new VarArgsSQLFunction(StandardBasicTypes.STRING, "", "||", ""));
registerFunction("mod", new SQLFunctionTemplate(StandardBasicTypes.INTEGER, "?1 % ?2"));
registerFunction("quote", new StandardSQLFunction("quote", StandardBasicTypes.STRING));
registerFunction("random", new NoArgSQLFunction("random", StandardBasicTypes.INTEGER));
registerFunction("round", new StandardSQLFunction("round"));
registerFunction("substr", new StandardSQLFunction("substr", StandardBasicTypes.STRING));
registerFunction("year", new SQLFunctionTemplate(StandardBasicTypes.INTEGER, "abs(strftime('%Y', ?1))"));
registerFunction("month", new SQLFunctionTemplate(StandardBasicTypes.INTEGER, "abs(strftime(strftime('%m', ?1))"));
registerFunction("day", new SQLFunctionTemplate(StandardBasicTypes.INTEGER, "abs(strftime(strftime('%d', ?1))"));
registerFunction("hour", new SQLFunctionTemplate(StandardBasicTypes.INTEGER, "abs(strftime(strftime('%H', ?1))"));
registerFunction("minute", new SQLFunctionTemplate(StandardBasicTypes.INTEGER, "abs(strftime(strftime('%M', ?1))"));
registerFunction("second", new SQLFunctionTemplate(StandardBasicTypes.INTEGER, "abs(strftime(strftime('%S', ?1))"));
registerFunction("trim", new AbstractAnsiTrimEmulationFunction() {
@Override
protected SQLFunction resolveBothSpaceTrimFunction() {
return new SQLFunctionTemplate(StandardBasicTypes.STRING, "trim(?1)");
}
@Override
protected SQLFunction resolveBothSpaceTrimFromFunction() {
return new SQLFunctionTemplate(StandardBasicTypes.STRING, "trim(?2)");
}
@Override
protected SQLFunction resolveLeadingSpaceTrimFunction() {
return new SQLFunctionTemplate(StandardBasicTypes.STRING, "ltrim(?1)");
}
@Override
protected SQLFunction resolveTrailingSpaceTrimFunction() {
return new SQLFunctionTemplate(StandardBasicTypes.STRING, "rtrim(?1)");
}
@Override
protected SQLFunction resolveBothTrimFunction() {
return new SQLFunctionTemplate(StandardBasicTypes.STRING, "trim(?1, ?2)");
}
@Override
protected SQLFunction resolveLeadingTrimFunction() {
return new SQLFunctionTemplate(StandardBasicTypes.STRING, "ltrim(?1, ?2)");
}
@Override
protected SQLFunction resolveTrailingTrimFunction() {
return new SQLFunctionTemplate(StandardBasicTypes.STRING, "rtrim(?1, ?2)");
}
});
uniqueDelegate = new SQLiteUniqueDelegate(this);
}
// database type mapping support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@Override
public String getCastTypeName(int code) {
// FIXME
return super.getCastTypeName(code);
}
// IDENTITY support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
private static final SQLiteDialectIdentityColumnSupport IDENTITY_COLUMN_SUPPORT = new SQLiteDialectIdentityColumnSupport();
@Override
public IdentityColumnSupport getIdentityColumnSupport() {
return IDENTITY_COLUMN_SUPPORT;
}
// limit/offset support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
private static final AbstractLimitHandler LIMIT_HANDLER = new AbstractLimitHandler() {
@Override
public String processSql(String sql, RowSelection selection) {
final boolean hasOffset = LimitHelper.hasFirstRow(selection);
return sql + (hasOffset ? " limit ? offset ?" : " limit ?");
}
@Override
public boolean supportsLimit() {
return true;
}
@Override
public boolean bindLimitParametersInReverseOrder() {
return true;
}
};
@Override
public LimitHandler getLimitHandler() {
return LIMIT_HANDLER;
}
// lock acquisition support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@Override
public boolean supportsLockTimeouts() {
// may be http://sqlite.org/c3ref/db_mutex.html ?
return false;
}
@Override
public String getForUpdateString() {
return "";
}
@Override
public boolean supportsOuterJoinForUpdate() {
return false;
}
/*
@Override
public boolean dropTemporaryTableAfterUse() {
return true; // temporary tables are only dropped when the connection is closed. If the connection is pooled...
}
*/
// current timestamp support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@Override
public boolean supportsCurrentTimestampSelection() {
return true;
}
@Override
public boolean isCurrentTimestampSelectStringCallable() {
return false;
}
@Override
public String getCurrentTimestampSelectString() {
return "select current_timestamp";
}
// SQLException support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
private static final int SQLITE_BUSY = 5;
private static final int SQLITE_LOCKED = 6;
private static final int SQLITE_IOERR = 10;
private static final int SQLITE_CORRUPT = 11;
private static final int SQLITE_NOTFOUND = 12;
private static final int SQLITE_FULL = 13;
private static final int SQLITE_CANTOPEN = 14;
private static final int SQLITE_PROTOCOL = 15;
private static final int SQLITE_TOOBIG = 18;
private static final int SQLITE_CONSTRAINT = 19;
private static final int SQLITE_MISMATCH = 20;
private static final int SQLITE_NOTADB = 26;
@Override
public SQLExceptionConversionDelegate buildSQLExceptionConversionDelegate() {
return new SQLExceptionConversionDelegate() {
@Override
public JDBCException convert(SQLException sqlException, String message, String sql) {
final int errorCode = JdbcExceptionHelper.extractErrorCode(sqlException);
if (errorCode == SQLITE_TOOBIG || errorCode == SQLITE_MISMATCH) {
return new DataException(message, sqlException, sql);
} else if (errorCode == SQLITE_BUSY || errorCode == SQLITE_LOCKED) {
return new LockAcquisitionException(message, sqlException, sql);
} else if ((errorCode >= SQLITE_IOERR && errorCode <= SQLITE_PROTOCOL) || errorCode == SQLITE_NOTADB) {
return new JDBCConnectionException(message, sqlException, sql);
}
// returning null allows other delegates to operate
return null;
}
};
}
@Override
public ViolatedConstraintNameExtracter getViolatedConstraintNameExtracter() {
return EXTRACTER;
}
private static final ViolatedConstraintNameExtracter EXTRACTER = new TemplatedViolatedConstraintNameExtracter() {
@Override
protected String doExtractConstraintName(SQLException sqle) throws NumberFormatException {
final int errorCode = JdbcExceptionHelper.extractErrorCode(sqle);
if (errorCode == SQLITE_CONSTRAINT) {
return extractUsingTemplate("constraint ", " failed", sqle.getMessage());
}
return null;
}
};
// union subclass support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@Override
public boolean supportsUnionAll() {
return true;
}
// DDL support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@Override
public boolean canCreateSchema() {
return false;
}
@Override
public boolean hasAlterTable() {
// As specified in NHibernate dialect
return false;
}
@Override
public boolean dropConstraints() {
return false;
}
@Override
public boolean qualifyIndexName() {
return false;
}
@Override
public String getAddColumnString() {
return "add column";
}
@Override
public String getDropForeignKeyString() {
throw new UnsupportedOperationException("No drop foreign key syntax supported by SQLiteDialect");
}
@Override
public String getAddForeignKeyConstraintString(String constraintName,
String[] foreignKey, String referencedTable, String[] primaryKey,
boolean referencesPrimaryKey) {
throw new UnsupportedOperationException("No add foreign key syntax supported by SQLiteDialect");
}
@Override
public String getAddPrimaryKeyConstraintString(String constraintName) {
throw new UnsupportedOperationException("No add primary key syntax supported by SQLiteDialect");
}
@Override
public boolean supportsCommentOn() {
return true;
}
@Override
public boolean supportsIfExistsBeforeTableName() {
return true;
}
/* not case insensitive for unicode characters by default (ICU extension needed)
public boolean supportsCaseInsensitiveLike() {
return true;
}
*/
@Override
public boolean doesReadCommittedCauseWritersToBlockReaders() {
// TODO Validate (WAL mode...)
return true;
}
@Override
public boolean doesRepeatableReadCauseReadersToBlockWriters() {
return true;
}
@Override
public boolean supportsTupleDistinctCounts() {
return false;
}
@Override
public int getInExpressionCountLimit() {
// Compile/runtime time option: http://sqlite.org/limits.html#max_variable_number
return 1000;
}
@Override
public UniqueDelegate getUniqueDelegate() {
return uniqueDelegate;
}
private static class SQLiteUniqueDelegate extends DefaultUniqueDelegate {
public SQLiteUniqueDelegate(Dialect dialect) {
super(dialect);
}
@Override
public String getColumnDefinitionUniquenessFragment(Column column) {
return " unique";
}
}
@Override
public String getSelectGUIDString() {
return "select hex(randomblob(16))";
}
@Override
public ScrollMode defaultScrollMode() {
return ScrollMode.FORWARD_ONLY;
}
}
这是 Hibernate 5.1
【讨论】：
尝试在 SQL 中查找“datepart”函数的用法。
这样的事情应该可以工作：
SELECT datewithouttime as datepart(dd,datefield)+'/'+datepart(mm,datefield)+"/"+datepart(yyyy,datefield) FROM tableName
【讨论】：
datepart 函数。